From: Laurent Pinchart laurent.pinchart@ideasonboard.com
[ 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@acm.org Fixes: c0efd232929c ("V4L/DVB (8145a): USB Video Class driver") Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Reviewed-by: Bart Van Assche bvanassche@acm.org Tested-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/usb/uvc/uvc_ctrl.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
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. */