This is a note to let you know that I've just added the patch titled
media: uvcvideo: Silence shift-out-of-bounds warning
to the 5.4-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-uvcvideo-silence-shift-out-of-bounds-warning.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a7e427b1fc0d6d6af62588d111095ad306b9c62e
Author: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Date: Wed Aug 19 01:56:49 2020 +0200
media: uvcvideo: Silence shift-out-of-bounds warning
[ Upstream commit 171994e498a0426cbe17f874c5c6af3c0af45200 ]
UBSAN reports a shift-out-of-bounds warning in uvc_get_le_value(). The
report is correct, but the issue should be harmless as the computed
value isn't used when the shift is negative. This may however cause
incorrect behaviour if a negative shift could generate adverse side
effects (such as a trap on some architectures for instance).
Regardless of whether that may happen or not, silence the warning as a
full WARN backtrace isn't nice.
Reported-by: Bart Van Assche <bvanassche@xxxxxxx>
Fixes: c0efd232929c ("V4L/DVB (8145a): USB Video Class driver")
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Tested-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index e399b9fad7574..a30a8a731eda8 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -773,12 +773,16 @@ static s32 uvc_get_le_value(struct uvc_control_mapping *mapping,
offset &= 7;
mask = ((1LL << bits) - 1) << offset;
- for (; bits > 0; data++) {
+ while (1) {
u8 byte = *data & mask;
value |= offset > 0 ? (byte >> offset) : (byte << (-offset));
bits -= 8 - (offset > 0 ? offset : 0);
+ if (bits <= 0)
+ break;
+
offset -= 8;
mask = (1 << bits) - 1;
+ data++;
}
/* Sign-extend the value if needed. */
