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Gaosheng Cui 5abbeebd82 tty: fix possible null-ptr-defer in spk_ttyio_release
Run the following tests on the qemu platform:

syzkaller:~# modprobe speakup_audptr
 input: Speakup as /devices/virtual/input/input4
 initialized device: /dev/synth, node (MAJOR 10, MINOR 125)
 speakup 3.1.6: initialized
 synth name on entry is: (null)
 synth probe

spk_ttyio_initialise_ldisc failed because tty_kopen_exclusive returned
failed (errno -16), then remove the module, we will get a null-ptr-defer
problem, as follow:

syzkaller:~# modprobe -r speakup_audptr
 releasing synth audptr
 BUG: kernel NULL pointer dereference, address: 0000000000000080
 #PF: supervisor write access in kernel mode
 #PF: error_code(0x0002) - not-present page
 PGD 0 P4D 0
 Oops: 0002 [#1] PREEMPT SMP PTI
 CPU: 2 PID: 204 Comm: modprobe Not tainted 6.1.0-rc6-dirty #1
 RIP: 0010:mutex_lock+0x14/0x30
 Call Trace:
 <TASK>
  spk_ttyio_release+0x19/0x70 [speakup]
  synth_release.part.6+0xac/0xc0 [speakup]
  synth_remove+0x56/0x60 [speakup]
  __x64_sys_delete_module+0x156/0x250
  ? fpregs_assert_state_consistent+0x1d/0x50
  do_syscall_64+0x37/0x90
  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 </TASK>
 Modules linked in: speakup_audptr(-) speakup
 Dumping ftrace buffer:

in_synth->dev was not initialized during modprobe, so we add check
for in_synth->dev to fix this bug.

Fixes: 4f2a81f3a8 ("speakup: Reference synth from tty and tty from synth")
Cc: stable <stable@kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20221202060633.217364-1-cuigaosheng1@huawei.com
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 16:24:04 +01:00
arch - Make sure the poking PGD is pinned for Xen PV as it requires it this way 2023-01-15 07:17:44 -06:00
block block-6.2-2023-01-13 2023-01-13 17:41:19 -06:00
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crypto This update includes the following changes: 2022-12-14 12:31:09 -08:00
Documentation ARM: 2023-01-13 14:41:50 -06:00
drivers tty: fix possible null-ptr-defer in spk_ttyio_release 2023-01-19 16:24:04 +01:00
fs 7 smb3 client fixes 2023-01-14 08:08:25 -06:00
include First batch of EFI fixes for v6.2: 2023-01-13 10:37:10 -06:00
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usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
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MAINTAINERS block-6.2-2023-01-13 2023-01-13 17:41:19 -06:00
Makefile Linux 6.2-rc4 2023-01-15 09:22:43 -06:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.