media: v4l2-core: explicitly clear ioctl input data
authorArnd Bergmann <arnd@arndb.de>
Mon, 14 Jun 2021 10:34:03 +0000 (12:34 +0200)
committerMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Thu, 17 Jun 2021 08:15:32 +0000 (10:15 +0200)
commit7b53cca764f9b291b7907fcd39d9e66ad728ee0b
treeaeff6b1de833af0fae3d919b0cca06470362431e
parentc344f07aa1b4ba38ca8fabe407a2afe2f436323c
media: v4l2-core: explicitly clear ioctl input data

As seen from a recent syzbot bug report, mistakes in the compat ioctl
implementation can lead to uninitialized kernel stack data getting used
as input for driver ioctl handlers.

The reported bug is now fixed, but it's possible that other related
bugs are still present or get added in the future. As the drivers need
to check user input already, the possible impact is fairly low, but it
might still cause an information leak.

To be on the safe side, always clear the entire ioctl buffer before
calling the conversion handler functions that are meant to initialize
them.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
drivers/media/v4l2-core/v4l2-ioctl.c