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>
---
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 6c37aa018ad5..b2cdee0f7763 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. */
--
Regards,
Laurent Pinchart
