* sanity checks belong before risky operation, not after it
* don't quit as soon as we'd found an entry
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
new helper: dir_relax(inode). Call when you are in location that will
_not_ be invalidated by directory modifications (block boundary, in case
of ext*). Returns whether the directory has survived (dropping i_mutex
allows rmdir to kill the sucker; if it returns false to us, ->iterate()
is obviously done)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
New method - ->iterate(file, ctx). That's the replacement for ->readdir();
it takes callback from ctx->actor, uses ctx->pos instead of file->f_pos and
calls dir_emit(ctx, ...) instead of filldir(data, ...). It does *not*
update file->f_pos (or look at it, for that matter); iterate_dir() does the
update.
Note that dir_emit() takes the offset from ctx->pos (and eventually
filldir_t will lose that argument).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
iterate_dir(): new helper, replacing vfs_readdir().
struct dir_context: contains the readdir callback (and will get more stuff
in it), embedded into whatever data that callback wants to deal with;
eventually, we'll be passing it to ->readdir() replacement instead of
(data,filldir) pair.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro pointed me to the fact that '->readdir()' and '->llseek()' have no
mutual exclusion, which means the 'ubifs_dir_llseek()' can be run while we are
in the middle of 'ubifs_readdir()'.
This means that 'file->private_data' can be freed while 'ubifs_readdir()' uses
it, and this is a very bad bug: not only 'ubifs_readdir()' can return garbage,
but this may corrupt memory and lead to all kinds of problems like crashes an
security holes.
This patch fixes the problem by using the 'file->f_version' field, which
'->llseek()' always unconditionally sets to zero. We set it to 1 in
'ubifs_readdir()' and whenever we detect that it became 0, we know there was a
seek and it is time to clear the state saved in 'file->private_data'.
I tested this patch by writing a user-space program which runds readdir and
seek in parallell. I could easily crash the kernel without these patches, but
could not crash it with these patches.
Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro pointed me to the fact that '->readdir()' and '->llseek()' have no
mutual exclusion, which means the 'ubifs_dir_llseek()' can be run while we are
in the middle of 'ubifs_readdir()'.
First of all, this means that 'file->private_data' can be freed while
'ubifs_readdir()' uses it. But this particular patch does not fix the problem.
This patch is only a preparation, and the fix will follow next.
In this patch we make 'ubifs_readdir()' stop using 'file->f_pos' directly,
because 'file->f_pos' can be changed by '->llseek()' at any point. This may
lead 'ubifs_readdir()' to returning inconsistent data: directory entry names
may correspond to incorrect file positions.
So here we introduce a local variable 'pos', read 'file->f_pose' once at very
the beginning, and then stick to 'pos'. The result of this is that when
'ubifs_dir_llseek()' changes 'file->f_pos' while we are in the middle of
'ubifs_readdir()', the latter "wins".
Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This is patch 3/3 of a patch set that cleans up pstore_register failure paths.
If efivars fails to register with pstore, there is no point to keeping
the 4 KB buffer around. It's only used by the pstore read/write routines.
Signed-off-by: Lenny Szubowicz <lszubowi@redhat.com>
Reported-by: Naotaka Hamaguchi <n.hamaguchi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This is patch 2/3 of a patch set that avoids what misleadingly appears
to be a error during boot:
ERST: Could not register with persistent store
This message is displayed if the system has a valid ACPI ERST table and the
pstore.backend kernel parameter has been used to disable use of ERST by
pstore. But this same message is used for errors that preclude registration.
In erst_init don't complain if the setting of kernel parameter pstore.backend
precludes use of ACPI ERST for pstore. Routine pstore_register will inform
about the facility that does register.
Also, don't leave a dangling pointer to deallocated mem for the pstore
buffer when registration fails.
Signed-off-by: Lenny Szubowicz <lszubowi@redhat.com>
Reported-by: Naotaka Hamaguchi <n.hamaguchi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This is patch 1/3 of a patch set that avoids what misleadingly appears
to be a error during boot:
ERST: Could not register with persistent store
This message is displayed if the system has a valid ACPI ERST table and the
pstore.backend kernel parameter has been used to disable use of ERST by
pstore. But this same message is used for errors that preclude registration.
As part of fixing this, return a unique error status from pstore_register
if the pstore.backend kernel parameter selects a specific facility other
than the requesting facility and check for this condition before any others.
This allows the caller to distinquish this benign case from the other failure
cases.
Also, print an informational console message about which facility
successfully registered as the pstore backend. Since there are various
kernel parameters, config build options, and boot-time errors that can
influence which facility registers with pstore, it's useful to have a
positive indication.
Signed-off-by: Lenny Szubowicz <lszubowi@redhat.com>
Reported-by: Naotaka Hamaguchi <n.hamaguchi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This fixes the problem that "init=" options may not be passed to kernel
correctly.
parse_mem_cmdline() of mn10300 arch gets rid of "mem=" string from
redboot_command_line. Then init_setup() parses the "init=" options from
static_command_line, which is a copy of redboot_command_line, and keeps
the pointer to the init options in execute_command variable.
Since the commit 026cee0 upstream (params: <level>_initcall-like kernel
parameters), static_command_line becomes overwritten by saved_command_line at
do_initcall_level(). Notice that saved_command_line is a command line
which includes "mem=" string.
As a result, execute_command may point to weird string by the length of
"mem=" parameter.
I noticed this problem when using the command line like this:
mem=128M console=ttyS0,115200 init=/bin/sh
Here is the processing flow of command line parameters.
start_kernel()
setup_arch(&command_line)
parse_mem_cmdline(cmdline_p)
* strcpy(boot_command_line, redboot_command_line);
* Remove "mem=xxx" from redboot_command_line.
* *cmdline_p = redboot_command_line;
setup_command_line(command_line) <-- command_line is redboot_command_line
* strcpy(saved_command_line, boot_command_line)
* strcpy(static_command_line, command_line)
parse_early_param()
strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
parse_early_options(tmp_cmdline);
parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
parse_args("Booting ..", static_command_line, ...);
init_setup() <-- save the pointer in execute_command
rest_init()
kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
At this point, execute_command points to "/bin/sh" string.
kernel_init()
kernel_init_freeable()
do_basic_setup()
do_initcalls()
do_initcall_level()
(*) strcpy(static_command_line, saved_command_line);
Here, execute_command gets to point to "200" string !!
Signed-off-by: David Howells <dhowells@redhat.com>
This fixes the following compile error:
CC block/scsi_ioctl.o
block/scsi_ioctl.c: In function 'sg_scsi_ioctl':
block/scsi_ioctl.c:449: error: invalid initializer
Signed-off-by: David Howells <dhowells@redhat.com>
