This is a note to let you know that I've just added the patch titled
media: v4l2-core: explicitly clear ioctl input data
to the 5.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-v4l2-core-explicitly-clear-ioctl-input-data.patch
and it can be found in the queue-5.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7b53cca764f9b291b7907fcd39d9e66ad728ee0b Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@xxxxxxxx>
Date: Mon, 14 Jun 2021 12:34:03 +0200
Subject: media: v4l2-core: explicitly clear ioctl input data
From: Arnd Bergmann <arnd@xxxxxxxx>
commit 7b53cca764f9b291b7907fcd39d9e66ad728ee0b upstream.
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@xxxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-ioctl.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -3124,8 +3124,10 @@ static int video_get_user(void __user *a
if (copy_from_user(parg, (void __user *)arg, n))
err = -EFAULT;
} else if (in_compat_syscall()) {
+ memset(parg, 0, n);
err = v4l2_compat_get_user(arg, parg, cmd);
} else {
+ memset(parg, 0, n);
#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME)
switch (cmd) {
case VIDIOC_QUERYBUF_TIME32:
Patches currently in stable-queue which might be from arnd@xxxxxxxx are
queue-5.13/media-subdev-disallow-ioctl-for-saa6588-davinci.patch
queue-5.13/media-v4l2-core-explicitly-clear-ioctl-input-data.patch
