Commit Graph

441 Commits

Author SHA1 Message Date
Tetsuo Handa
ffb324e6f8 tty: vt: always invoke vc->vc_sw->con_resize callback
syzbot is reporting OOB write at vga16fb_imageblit() [1], for
resize_screen() from ioctl(VT_RESIZE) returns 0 without checking whether
requested rows/columns fit the amount of memory reserved for the graphical
screen if current mode is KD_GRAPHICS.

----------
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <sys/ioctl.h>
  #include <linux/kd.h>
  #include <linux/vt.h>

  int main(int argc, char *argv[])
  {
        const int fd = open("/dev/char/4:1", O_RDWR);
        struct vt_sizes vt = { 0x4100, 2 };

        ioctl(fd, KDSETMODE, KD_GRAPHICS);
        ioctl(fd, VT_RESIZE, &vt);
        ioctl(fd, KDSETMODE, KD_TEXT);
        return 0;
  }
----------

Allow framebuffer drivers to return -EINVAL, by moving vc->vc_mode !=
KD_GRAPHICS check from resize_screen() to fbcon_resize().

Link: https://syzkaller.appspot.com/bug?extid=1f29e126cf461c4de3b3 [1]
Reported-by: syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-15 08:12:12 -07:00
Linus Torvalds
adc12a7407 Merge branch 'resizex' (patches from Maciej)
Merge VT_RESIZEX fixes from Maciej Rozycki:
 "I got to the bottom of the issue with VT_RESIZEX recently discussed
  and came up with this small patch series, fixing an additional issue
  that I originally thought might be broken VGA hardware emulation with
  my laptop, which however turned out to be intertwined with the
  original problem and also a regression introduced somewhat later.

  The fix for that because the first patch, and then to make backporting
  feasible I had to put a revert of the offending change from last
  September next, followed by a proper fix for the framebuffer issue
  that change had tried to address.

  See individual change descriptions for details.

  These have been verified with true VGA hardware (a Trident TVGA8900
  ISA video adapter) using various combinations of `svgatextmode' and
  `setfont' command invocations to change both the VT size and the font
  size, and also switching between the text console and X11, both by
  starting/stopping the X server and by switching between VTs.

  All this to ensure bringing the behaviour of VGA text console back to
  correct operation as it used to be with Linux 2.6.18"

* emailed patches from Maciej W. Rozycki <macro@orcam.me.uk>:
  vt: Fix character height handling with VT_RESIZEX
  vt_ioctl: Revert VT_RESIZEX parameter handling removal
  vgacon: Record video mode changes with VT_RESIZEX
2021-05-13 11:12:51 -07:00
Maciej W. Rozycki
860dafa902 vt: Fix character height handling with VT_RESIZEX
Restore the original intent of the VT_RESIZEX ioctl's `v_clin' parameter
which is the number of pixel rows per character (cell) rather than the
height of the font used.

For framebuffer devices the two values are always the same, because the
former is inferred from the latter one.  For VGA used as a true text
mode device these two parameters are independent from each other: the
number of pixel rows per character is set in the CRT controller, while
font height is in fact hardwired to 32 pixel rows and fonts of heights
below that value are handled by padding their data with blanks when
loaded to hardware for use by the character generator.  One can change
the setting in the CRT controller and it will update the screen contents
accordingly regardless of the font loaded.

The `v_clin' parameter is used by the `vgacon' driver to set the height
of the character cell and then the cursor position within.  Make the
parameter explicit then, by defining a new `vc_cell_height' struct
member of `vc_data', set it instead of `vc_font.height' from `v_clin' in
the VT_RESIZEX ioctl, and then use it throughout the `vgacon' driver
except where actual font data is accessed which as noted above is
independent from the CRTC setting.

This way the framebuffer console driver is free to ignore the `v_clin'
parameter as irrelevant, as it always should have, avoiding any issues
attempts to give the parameter a meaning there could have caused, such
as one that has led to commit 988d076336 ("vt_ioctl: make VT_RESIZEX
behave like VT_RESIZE"):

 "syzbot is reporting UAF/OOB read at bit_putcs()/soft_cursor() [1][2],
  for vt_resizex() from ioctl(VT_RESIZEX) allows setting font height
  larger than actual font height calculated by con_font_set() from
  ioctl(PIO_FONT). Since fbcon_set_font() from con_font_set() allocates
  minimal amount of memory based on actual font height calculated by
  con_font_set(), use of vt_resizex() can cause UAF/OOB read for font
  data."

The problem first appeared around Linux 2.5.66 which predates our repo
history, but the origin could be identified with the old MIPS/Linux repo
also at: <git://git.kernel.org/pub/scm/linux/kernel/git/ralf/linux.git>
as commit 9736a3546de7 ("Merge with Linux 2.5.66."), where VT_RESIZEX
code in `vt_ioctl' was updated as follows:

 		if (clin)
-			video_font_height = clin;
+			vc->vc_font.height = clin;

making the parameter apply to framebuffer devices as well, perhaps due
to the use of "font" in the name of the original `video_font_height'
variable.  Use "cell" in the new struct member then to avoid ambiguity.

References:

[1] https://syzkaller.appspot.com/bug?id=32577e96d88447ded2d3b76d71254fb855245837
[2] https://syzkaller.appspot.com/bug?id=6b8355d27b2b94fb5cedf4655e3a59162d9e48e3

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org # v2.6.12+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-13 11:00:18 -07:00
Maciej W. Rozycki
a90c275eb1 vt_ioctl: Revert VT_RESIZEX parameter handling removal
Revert the removal of code handling extra VT_RESIZEX ioctl's parameters
beyond those that VT_RESIZE supports, fixing a functional regression
causing `svgatextmode' not to resize the VT anymore.

As a consequence of the reverted change when the video adapter is
reprogrammed from the original say 80x25 text mode using a 9x16
character cell (720x400 pixel resolution) to say 80x37 text mode and the
same character cell (720x592 pixel resolution), the VT geometry does not
get updated and only upper two thirds of the screen are used for the VT,
and the lower part remains blank.  The proportions change according to
text mode geometries chosen.

Revert the change verbatim then, bringing back previous VT resizing.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: 988d076336 ("vt_ioctl: make VT_RESIZEX behave like VT_RESIZE")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-13 11:00:18 -07:00
Masahiro Yamada
9009b45581 .gitignore: prefix local generated files with a slash
The pattern prefixed with '/' matches files in the same directory,
but not ones in sub-directories.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Andra Paraschiv <andraprs@amazon.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Gabriel Krisman Bertazi <krisman@collabora.com>
2021-05-02 00:43:35 +09:00
Pavel Skripkin
211b4d42b7 tty: fix memory leak in vc_deallocate
syzbot reported memory leak in tty/vt.
The problem was in VT_DISALLOCATE ioctl cmd.
After allocating unimap with PIO_UNIMAP it wasn't
freed via VT_DISALLOCATE, but vc_cons[currcons].d was
zeroed.

Reported-by: syzbot+bcc922b19ccc64240b42@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210327214443.21548-1-paskripkin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-28 14:16:47 +02:00
Bhaskar Chowdhury
22fce66c19 tty: vt: Mundane typo fix in the file vt.c
s/spurrious/spurious/
s/worse/worst/

Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Link: https://lore.kernel.org/r/20210314062716.28539-1-unixbhaskar@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-23 10:39:31 +01:00
Andy Shevchenko
c6a419afe3 vt: keyboard, Fix typo in the doc for vt_get_shift_state()
Kernel documentation validator is not happy:

.../keyboard.c:2195: warning: expecting prototype for vt_get_shiftstate(). Prototype was for vt_get_shift_state() instead

This is due to typo, fix it here.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210303083229.75784-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-23 10:39:27 +01:00
Ahmed S. Darwish
151db8c08c vt_ioctl: Remove in_interrupt() check
reset_vc() uses a "!in_interrupt()" conditional before resetting the
palettes, which is a blocking operation. Since commit
   8b6312f4dc ("[PATCH] vt: refactor console SAK processing")

all calls are invoked from a workqueue process context, with the
blocking console lock always acquired.

Remove the "!in_interrupt()" check.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20210208181615.381861-2-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-09 11:45:04 +01:00
Emil Renner Berthing
9159835a97 vt: keyboard, use new API for keyboard_tasklet
This converts the keyboard_tasklet to use the new API in
commit 12cc923f1c ("tasklet: Introduce new initialization API")

The new API changes the argument passed to the callback function, but
fortunately the argument isn't used so it is straight forward to use
DECLARE_TASKLET_DISABLED() rather than DECLARE_TASKLET_DISABLED_OLD().

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Link: https://lore.kernel.org/r/20210127164222.13220-1-kernel@esmil.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27 18:08:07 +01:00
Jiri Slaby
ff2047fb75 vt: drop old FONT ioctls
Drop support for these ioctls:
* PIO_FONT, PIO_FONTX
* GIO_FONT, GIO_FONTX
* PIO_FONTRESET

As was demonstrated by commit 90bfdeef83 (tty: make FONTX ioctl use
the tty pointer they were actually passed), these ioctls are not used
from userspace, as:
1) they used to be broken (set up font on current console, not the open
   one) and racy (before the commit above)
2) KDFONTOP ioctl is used for years instead

Note that PIO_FONTRESET is defunct on most systems as VGA_CONSOLE is set
on them for ages. That turns on BROKEN_GRAPHICS_PROGRAMS which makes
PIO_FONTRESET just return an error.

We are removing KD_FONT_FLAG_OLD here as it was used only by these
removed ioctls. kd.h header exists both in kernel and uapi headers, so
we can remove the kernel one completely. Everyone includeing kd.h will
now automatically get the uapi one.

There are now unused definitions of the ioctl numbers and "struct
consolefontdesc" in kd.h, but as it is a uapi header, I am not touching
these.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-8-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07 16:17:31 +01:00
Jiri Slaby
9777f8e60e vt/consolemap: do font sum unsigned
The constant 20 makes the font sum computation signed which can lead to
sign extensions and signed wraps. It's not much of a problem as we build
with -fno-strict-overflow. But if we ever decide not to, be ready, so
switch the constant to unsigned.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07 16:17:31 +01:00
Jiri Slaby
e81de384af vt: keyboard, defkeymap.c_shipped, approach the unicode table
Commit 5ce2087ed0 (Fix default compose table initialization) fixed
unicode table so that the values are not sign extended. The upstream
(kbd package) chose a different approach. They use hexadecimal values.
So use the same, so that the output of loadkeys and our shipped file
correspond more to each other.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07 16:17:31 +01:00
Jiri Slaby
f14e039485 vt: keyboard, defkeymap.c_shipped, approach the definitions
loadkeys (from kbd) generates 'unsigned short' instead of 'u_short'
since 2.0.3. It also marks maps as 'static' for longer than kbd's
history.

So adapt the shipped defkeymap.c to conform more to loadkeys output.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07 16:17:31 +01:00
Jiri Slaby
a18a9da82c vt: keyboard, make keyboard_tasklet local
Now that the last extern user of the tasklet (set_leds) is in
keyboard.c, we can make keyboard_tasklet local to this unit too.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07 16:17:31 +01:00
Jiri Slaby
63f24a7faf vt: move set_leds to keyboard.c
set_leds and compute_shiftstate are called from a single place in vt.c.
Let's combine these two into vt_set_leds_compute_shiftstate. This allows
for making keyboard_tasklet local in the next patch.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07 16:17:31 +01:00
Yan.Gao
fa26b3263f tty: Fix whitespace inconsistencies in vt_io_ioctl
Replaces spaces with tabs for indentation.

Signed-off-by: Yan.Gao <gao.yanB@h3c.com>
Link: https://lore.kernel.org/r/20201209030551.48029-1-gao.yanB@h3c.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-09 15:35:43 +01:00
Andy Shevchenko
cb215da836 vt: keyboard, make use of assign_bit() API
We have for some time the assign_bit() API to replace open coded

	if (foo)
		set_bit(n, bar);
	else
		clear_bit(n, bar);

Use this API in VT keyboard library code.

Acked-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20201109105601.47159-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-12 09:43:51 +01:00
Andy Shevchenko
6d2c52a83b vt: keyboard, replace numbers with \r, \n where appropriate
Instead of 10, 13 use \n, \r respectively.

Acked-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20201109105601.47159-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-12 09:43:51 +01:00
Andy Shevchenko
c050a97d05 vt: keyboard, use BIT() macro instead of open coded variants
There are few places when BIT() macro is suitable and makes code
easier to understand.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20201109105601.47159-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-12 09:43:50 +01:00
Greg Kroah-Hartman
9b085d6e88 Merge 5.10-rc3 into tty-next
We need the TTY/vt/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-09 10:37:10 +01:00
Linus Torvalds
bbc821849e TTY/Serial fixes for 5.10-rc3
Here are a small number of small tty and serial fixes for some reported
 problems for the tty core, vt code, and some serial drivers.
 
 They include fixes for:
 	- a buggy and obsolete vt font ioctl removal
 	- 8250_mtk serial baudrate runtime warnings
 	- imx serial earlycon build configuration fix
 	- txx9 serial driver error path cleanup issues
 	- tty core fix in release_tty that can be triggered by trying to
 	  bind an invalid serial port name to a speakup console device
 
 Almost all of these have been in linux-next without any problems, the
 only one that hasn't, just deletes code :)
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are a small number of small tty and serial fixes for some
  reported problems for the tty core, vt code, and some serial drivers.

  They include fixes for:

   - a buggy and obsolete vt font ioctl removal

   - 8250_mtk serial baudrate runtime warnings

   - imx serial earlycon build configuration fix

   - txx9 serial driver error path cleanup issues

   - tty core fix in release_tty that can be triggered by trying to bind
     an invalid serial port name to a speakup console device

  Almost all of these have been in linux-next without any problems, the
  only one that hasn't, just deletes code :)"

* tag 'tty-5.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  vt: Disable KD_FONT_OP_COPY
  tty: fix crash in release_tty if tty->port is not set
  serial: txx9: add missing platform_driver_unregister() on error in serial_txx9_init
  tty: serial: imx: enable earlycon by default if IMX_SERIAL_CONSOLE is enabled
  serial: 8250_mtk: Fix uart_get_baud_rate warning
2020-11-08 11:28:08 -08:00
Daniel Vetter
3c4e0dff20 vt: Disable KD_FONT_OP_COPY
It's buggy:

On Fri, Nov 06, 2020 at 10:30:08PM +0800, Minh Yuan wrote:
> We recently discovered a slab-out-of-bounds read in fbcon in the latest
> kernel ( v5.10-rc2 for now ).  The root cause of this vulnerability is that
> "fbcon_do_set_font" did not handle "vc->vc_font.data" and
> "vc->vc_font.height" correctly, and the patch
> <https://lkml.org/lkml/2020/9/27/223> for VT_RESIZEX can't handle this
> issue.
>
> Specifically, we use KD_FONT_OP_SET to set a small font.data for tty6, and
> use  KD_FONT_OP_SET again to set a large font.height for tty1. After that,
> we use KD_FONT_OP_COPY to assign tty6's vc_font.data to tty1's vc_font.data
> in "fbcon_do_set_font", while tty1 retains the original larger
> height. Obviously, this will cause an out-of-bounds read, because we can
> access a smaller vc_font.data with a larger vc_font.height.

Further there was only one user ever.
- Android's loadfont, busybox and console-tools only ever use OP_GET
  and OP_SET
- fbset documentation only mentions the kernel cmdline font: option,
  not anything else.
- systemd used OP_COPY before release 232 published in Nov 2016

Now unfortunately the crucial report seems to have gone down with
gmane, and the commit message doesn't say much. But the pull request
hints at OP_COPY being broken

https://github.com/systemd/systemd/pull/3651

So in other words, this never worked, and the only project which
foolishly every tried to use it, realized that rather quickly too.

Instead of trying to fix security issues here on dead code by adding
missing checks, fix the entire thing by removing the functionality.

Note that systemd code using the OP_COPY function ignored the return
value, so it doesn't matter what we're doing here really - just in
case a lone server somewhere happens to be extremely unlucky and
running an affected old version of systemd. The relevant code from
font_copy_to_all_vcs() in systemd was:

	/* copy font from active VT, where the font was uploaded to */
	cfo.op = KD_FONT_OP_COPY;
	cfo.height = vcs.v_active-1; /* tty1 == index 0 */
	(void) ioctl(vcfd, KDFONTOP, &cfo);

Note this just disables the ioctl, garbage collecting the now unused
callbacks is left for -next.

v2: Tetsuo found the old mail, which allowed me to find it on another
archive. Add the link too.

Acked-by: Peilin Ye <yepeilin.cs@gmail.com>
Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
References: https://lists.freedesktop.org/archives/systemd-devel/2016-June/036935.html
References: https://github.com/systemd/systemd/pull/3651
Cc: Greg KH <greg@kroah.com>
Cc: Peilin Ye <yepeilin.cs@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://lore.kernel.org/r/20201108153806.3140315-1-daniel.vetter@ffwll.ch
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-08 19:35:06 +01:00
Lee Jones
d3e3232e7b tty: vt: consolemap: Demote weakly documented function header
Fixes the following W=1 kernel build warning(s):

 drivers/tty/vt/consolemap.c:739: warning: Function parameter or member 'ct' not described in 'con_get_unimap'
 drivers/tty/vt/consolemap.c:739: warning: Function parameter or member 'uct' not described in 'con_get_unimap'
 drivers/tty/vt/consolemap.c:739: warning: Function parameter or member 'list' not described in 'con_get_unimap'

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Jakub Jelinek <jj@ultra.linux.cz>
Cc: Stanislav Voronyi <stas@cnti.uanet.kharkov.ua>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104193549.4026187-10-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-06 10:49:27 +01:00
Jiri Slaby
c35f638fc2 vt: keyboard, use tty_insert_flip_string in puts_queue
'puts_queue' currently loops over characters and employs the full tty
buffer machinery for every character. Do the buffer allocation only once
and copy all the character at once. This is achieved using
tty_insert_flip_string instead of loop+tty_insert_flip_char.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-17-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:39 +01:00
Jiri Slaby
2389cdc360 vt: keyboard, use find_next_bit in kbd_match
Instead of a 'for' loop with 'test_bit's to find a bit in a range, use
find_next_bit to achieve the same in a simpler and faster manner.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-16-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:39 +01:00
Jiri Slaby
6dee84d6be vt: keyboard, make HW_RAW a function
Instead of a multiline macro, convert HW_RAW to an inline function. It
allows for type checking of the parameter. And given we split the code
into two tests, it is now more readable too.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-15-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
cb58a50460 vt: keyboard, union perm checks in vt_do_kdgkb_ioctl
Do the permission check on a single place. That is where perm is
really checked.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-14-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
4e1404a5cd vt: keyboard, extract and simplify vt_kdskbsent
Setting of function key strings is now very complex. It uses a global
buffer 'func_buf' which is prefilled in defkeymap.c_shipped. Then there
is also an index table called 'func_table'. So initially, we have
something like this:
char func_buf[] =	"\e[[A\0" // for F1
			"\e[[B\0" // for F2
			...;
char *func_table[] = {
	func_buf + 0, // for F1
	func_buf + 5, // for F2
	... }

When a user changes some specific func string by KDSKBSENT, it is
changed in 'func_buf'. If it is shorter or equal to the current one, it
is handled by a very quick 'strcpy'.

When the user's string is longer, the whole 'func_buf' is reallocated to
allow expansion somewhere in the middle. The buffer before the user's
string is copied, the user's string appended and the rest appended too.
Now, the index table (func_table) needs to be recomputed, of course.
One more complication is the held spinlock -- we have to unlock,
reallocate, lock again and do the whole thing again to be sure noone
raced with us.

In this patch, we chose completely orthogonal approach: when the user's
string is longer than the current one, we simply assign the 'kstrdup'ed
copy to the index table (func_table) and modify func_buf in no way. We
only need to make sure we free the old entries. So we need a bitmap
is_kmalloc and free the old entries (but not the original func_buf
rodata string).

Also note that we do not waste so much space as previous approach. We
only allocate space for single entries which are longer, while before,
the whole buffer was duplicated plus space for the longer string.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-12-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
07edff9265 vt: keyboard, reorder user buffer handling in vt_do_kdgkb_ioctl
KDGKBSENT (the getter) needs only 'user_kdgkb->kb_func' from the
userspace, i.e. the index. Then it needs a buffer for a local copy of
'kb_string'.

KDSKBSENT (the setter) needs a copy up to the length of
'user_kdgkb->kb_string'.

That means, we obtain the index before the switch-case and use it in
both paths and:
1) allocate full space in the getter case, and
2) copy the string only in the setter case. We do it by strndup_user
   helper now which was not available when this function was written.

Given we copy the two members of 'struct kbsentry' separately, we no
longer need a local definition. Hence we need to change all the sizeofs
here too.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-11-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
9788c950ed vt: keyboard, rename i to kb_func in vt_do_kdgkb_ioctl
There are too many one-letter variables in vt_do_kdgkb_ioctl which is
rather confusing.  Rename 'i' to 'kb_func' and change its type to be the
same as its originating value (struct kbsentry.kb_func) -- unsigned
char.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-10-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
fe45d65786 vt: keyboard, use bool for rep
rep is used as a bool in the code, so declare it as such.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-9-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
2939840c99 vt: keyboard, use DECLARE_BITMAP for key_down
key_down is sued as a bitmap using test_bit, set_bit and similar.
So declare it using DECLARE_BITMAP to make it obvious even from the
declaration.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-8-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
ee1cf8a582 vt: keyboard, union perm checks in vt_do_kdsk_ioctl
Do the permission check on a single place. That is where perm is really
checked.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
fe6416e126 vt: keyboard, extract vt_kdgkbent and vt_kdskbent
Split vt_do_kdsk_ioctl into three functions:
* getter (KDGKBENT/vt_kdgkbent)
* setter (KDSKBENT/vt_kdskbent)
* switch-case helper (vt_do_kdsk_ioctl)

This eliminates the need of ugly one-letter macros as we use parameters
now:
* i aka tmp.kb_index -> idx
* s aka tmp.kb_table -> map
* v aka tmp.kb_value -> val

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
e27979dace vt: keyboard, clean up max_vals
Define one limit per line and index them by their index, so that it is
clear what is what.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
877a9c6a04 vt: keyboard, sort includes
There are many includes and it is hard to check if something is there or
not. So sort them alphabetically.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:38 +01:00
Jiri Slaby
0df97c7b5b vt: keyboard, include linux/spinlock.h
We use spin locks, but don't include linux/spinlock.h in keyboards.c. So
fix this up.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:37 +01:00
Jiri Slaby
6b8f8313c3 vt: keyboard, remove ctrl_alt_del declaration
ctrl_alt_del is already declared in linux/reboot.h which we include. So
remove this second (superfluous) declaration.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-04 16:43:37 +01:00
Linus Torvalds
90bfdeef83 tty: make FONTX ioctl use the tty pointer they were actually passed
Some of the font tty ioctl's always used the current foreground VC for
their operations.  Don't do that then.

This fixes a data race on fg_console.

Side note: both Michael Ellerman and Jiri Slaby point out that all these
ioctls are deprecated, and should probably have been removed long ago,
and everything seems to be using the KDFONTOP ioctl instead.

In fact, Michael points out that it looks like busybox's loadfont
program seems to have switched over to using KDFONTOP exactly _because_
of this bug (ahem.. 12 years ago ;-).

Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-02 14:49:17 -08:00
Jiri Slaby
d546547903 vt_ioctl: fix GIO_UNIMAP regression
In commit 5ba1278787, we shuffled with the check of 'perm'. But my
brain somehow inverted the condition in 'do_unimap_ioctl' (I thought
it is ||, not &&), so GIO_UNIMAP stopped working completely.

Move the 'perm' checks back to do_unimap_ioctl and do them right again.
In fact, this reverts this part of code to the pre-5ba127878722 state.
Except 'perm' is now a bool.

Fixes: 5ba1278787 ("vt_ioctl: move perm checks level up")
Cc: stable@vger.kernel.org
Reported-by: Fabian Vogt <fvogt@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201026055419.30518-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-28 13:41:17 +01:00
Jiri Slaby
82e61c3909 vt: keyboard, extend func_buf_lock to readers
Both read-side users of func_table/func_buf need locking. Without that,
one can easily confuse the code by repeatedly setting altering strings
like:
while (1)
	for (a = 0; a < 2; a++) {
		struct kbsentry kbs = {};
		strcpy((char *)kbs.kb_string, a ? ".\n" : "88888\n");
		ioctl(fd, KDSKBSENT, &kbs);
	}

When that program runs, one can get unexpected output by holding F1
(note the unxpected period on the last line):
.
88888
.8888

So protect all accesses to 'func_table' (and func_buf) by preexisting
'func_buf_lock'.

It is easy in 'k_fn' handler as 'puts_queue' is expected not to sleep.
On the other hand, KDGKBSENT needs a local (atomic) copy of the string
because copy_to_user can sleep. Use already allocated, but unused
'kbs->kb_string' for that purpose.

Note that the program above needs at least CAP_SYS_TTY_CONFIG.

This depends on the previous patch and on the func_buf_lock lock added
in commit 46ca3f735f (tty/vt: fix write/write race in ioctl(KDSKBSENT)
handler) in 5.2.

Likely fixes CVE-2020-25656.

Cc: <stable@vger.kernel.org>
Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201019085517.10176-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-28 13:41:02 +01:00
Jiri Slaby
6ca03f9052 vt: keyboard, simplify vt_kdgkbsent
Use 'strlen' of the string, add one for NUL terminator and simply do
'copy_to_user' instead of the explicit 'for' loop. This makes the
KDGKBSENT case more compact.

The only thing we need to take care about is NULL 'func_table[i]'. Use
an empty string in that case.

The original check for overflow could never trigger as the func_buf
strings are always shorter or equal to 'struct kbsentry's.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201019085517.10176-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-28 13:41:02 +01:00
Tetsuo Handa
988d076336 vt_ioctl: make VT_RESIZEX behave like VT_RESIZE
syzbot is reporting UAF/OOB read at bit_putcs()/soft_cursor() [1][2], for
vt_resizex() from ioctl(VT_RESIZEX) allows setting font height larger than
actual font height calculated by con_font_set() from ioctl(PIO_FONT).
Since fbcon_set_font() from con_font_set() allocates minimal amount of
memory based on actual font height calculated by con_font_set(),
use of vt_resizex() can cause UAF/OOB read for font data.

VT_RESIZEX was introduced in Linux 1.3.3, but it is unclear that what
comes to the "+ more" part, and I couldn't find a user of VT_RESIZEX.

  #define VT_RESIZE   0x5609 /* set kernel's idea of screensize */
  #define VT_RESIZEX  0x560A /* set kernel's idea of screensize + more */

So far we are not aware of syzbot reports caused by setting non-zero value
to v_vlin parameter. But given that it is possible that nobody is using
VT_RESIZEX, we can try removing support for v_clin and v_vlin parameters.

Therefore, this patch effectively makes VT_RESIZEX behave like VT_RESIZE,
with emitting a message if somebody is still using v_clin and/or v_vlin
parameters.

[1] https://syzkaller.appspot.com/bug?id=32577e96d88447ded2d3b76d71254fb855245837
[2] https://syzkaller.appspot.com/bug?id=6b8355d27b2b94fb5cedf4655e3a59162d9e48e3

Reported-by: syzbot <syzbot+b308f5fd049fbbc6e74f@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+16469b5e8e5a72e9131e@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/4933b81b-9b1a-355b-df0e-9b31e8280ab9@i-love.sakura.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-27 14:17:43 +02:00
Greg Kroah-Hartman
8f49a2fe8e Linux 5.9-rc3
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Merge 5.9-rc3 into tty-next

We need the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-31 07:19:25 +02:00
Linus Torvalds
15bc20c6af TTY/Serial fixes for 5.9-rc3
Here are a few small TTY/Serial/vt fixes for 5.9-rc3
 
 Included in here are:
 	- qcom serial fixes
 	- vt ioctl and core bugfixes
 	- pl011 serial driver fixes
 	- 8250 serial driver fixes
 	- other misc serial driver fixes
 
 and for good measure:
 	- fbcon fix for syzbot found problem.
 
 All of these have been in linux-next for a while with no reported
 issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are a few small TTY/Serial/vt fixes for 5.9-rc3

  Included in here are:
   - qcom serial fixes
   - vt ioctl and core bugfixes
   - pl011 serial driver fixes
   - 8250 serial driver fixes
   - other misc serial driver fixes

  and for good measure:
   - fbcon fix for syzbot found problem.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: serial: imx: add dependence and build for earlycon
  serial: samsung: Removes the IRQ not found warning
  serial: 8250: change lock order in serial8250_do_startup()
  serial: stm32: avoid kernel warning on absence of optional IRQ
  serial: pl011: Fix oops on -EPROBE_DEFER
  serial: pl011: Don't leak amba_ports entry on driver register error
  serial: 8250_exar: Fix number of ports for Commtech PCIe cards
  tty: serial: qcom_geni_serial: Drop __init from qcom_geni_console_setup
  serial: qcom_geni_serial: Fix recent kdb hang
  vt_ioctl: change VT_RESIZEX ioctl to check for error return from vc_resize()
  fbcon: prevent user font height or width change from causing potential out-of-bounds access
  vt: defer kfree() of vc_screenbuf in vc_do_resize()
2020-08-26 10:58:20 -07:00
Jiri Slaby
52c3c3a592 Revert "vc_screen: extract vcs_read_buf_header"
This reverts commit b1c32fcfad, because
Syzkaller reports a use-after-free, a write in vcs_read:

BUG: KASAN: use-after-free in vcs_read_buf drivers/tty/vt/vc_screen.c:357 [inline]
BUG: KASAN: use-after-free in vcs_read+0xaa7/0xb40 drivers/tty/vt/vc_screen.c:449
Write of size 2 at addr ffff8880a8014000 by task syz-executor.5/16936
CPU: 1 PID: 16936 Comm: syz-executor.5 Not tainted 5.9.0-rc1-next-20200820-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
...
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 vcs_read_buf drivers/tty/vt/vc_screen.c:357 [inline]
 vcs_read+0xaa7/0xb40 drivers/tty/vt/vc_screen.c:449

There are two issues with the patch:
1) vcs_read rounds the 'count' *up* to an even number. So if we read odd
   bytes from the header (3 bytes in the reproducer), the second byte of
   a (2-byte/ushort) write to temporary con_buf won't fit. It is because
   with the patch applied, we only subtract the real number read (3 bytes)
   and not the whole header (4 bytes).

2) in this scenario, we perform unaligned accesses now: there are
   2-byte/ushort writes to odd addresses. Due to the same reason as
   above.

Revert this for now, re-think and retry later.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: syzbot+ad1f53726c3bd11180cb@syzkaller.appspotmail.com
Fixes: b1c32fcfad ("vc_screen: extract vcs_read_buf_header")
Cc: akpm@linux-foundation.org
Cc: nico@fluxnic.net
Link: https://lore.kernel.org/r/20200824095425.4376-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-24 19:51:56 +02:00
Gustavo A. R. Silva
df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00
Jiri Slaby
ea239f1e32 tty: vt, fix kernel-doc
As in the previous patches, fix kernel-doc in vt.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200818085655.12071-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-18 13:51:18 +02:00
Jiri Slaby
a89313825b vc_screen: prune macros
Do not undefine random words. I guess this was here as there were macros
with such generic names somewhere. I very doubt they still exist. So
drop these.

And remove a spare blank line.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200818085706.12163-16-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-18 13:45:22 +02:00