diff options
author | Shuah Khan <shuahkh@osg.samsung.com> | 2016-06-10 14:37:23 -0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-05-27 16:40:25 +0200 |
commit | b882fcc49cb6c95259508766624d08fc516cd672 (patch) | |
tree | 7ce60604cc9bce238a90bd0ebb01fdbb45af70af /arch/frv/boot | |
parent | bbb3ce60dd698ec19fc7d5ff9fc61e7bedb6b9a4 (diff) |
media: fix media devnode ioctl/syscall and unregister race
commit 6f0dd24a084a17f9984dd49dffbf7055bf123993 upstream.
Media devnode open/ioctl could be in progress when media device unregister
is initiated. System calls and ioctls check media device registered status
at the beginning, however, there is a window where unregister could be in
progress without changing the media devnode status to unregistered.
process 1 process 2
fd = open(/dev/media0)
media_devnode_is_registered()
(returns true here)
media_device_unregister()
(unregister is in progress
and devnode isn't
unregistered yet)
...
ioctl(fd, ...)
__media_ioctl()
media_devnode_is_registered()
(returns true here)
...
media_devnode_unregister()
...
(driver releases the media device
memory)
media_device_ioctl()
(By this point
devnode->media_dev does not
point to allocated memory.
use-after free in in mutex_lock_nested)
BUG: KASAN: use-after-free in mutex_lock_nested+0x79c/0x800 at addr
ffff8801ebe914f0
Fix it by clearing register bit when unregister starts to avoid the race.
process 1 process 2
fd = open(/dev/media0)
media_devnode_is_registered()
(could return true here)
media_device_unregister()
(clear the register bit,
then start unregister.)
...
ioctl(fd, ...)
__media_ioctl()
media_devnode_is_registered()
(return false here, ioctl
returns I/O error, and
will not access media
device memory)
...
media_devnode_unregister()
...
(driver releases the media device
memory)
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reported-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Tested-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
[bwh: Backported to 4.4: adjut filename, context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/frv/boot')
0 files changed, 0 insertions, 0 deletions