Commit 171994e4 authored by Laurent Pinchart's avatar Laurent Pinchart Committed by Mauro Carvalho Chehab
Browse files

media: uvcvideo: Silence shift-out-of-bounds warning 



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: default avatarBart Van Assche <bvanassche@acm.org>
Fixes: c0efd232 ("V4L/DVB (8145a): USB Video Class driver")
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Tested-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent f875bcc3

drivers/media/usb/uvc/uvc_ctrl.c

+5 −1
Original line number Diff line number Diff line
@@ -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. */