This is a note to let you know that I've just added the patch titled HID: core: detect and skip invalid inputs to snto32() to the 5.11-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: hid-core-detect-and-skip-invalid-inputs-to-snto32.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 41b57b2c88f9b5a2c044b6aab2f9950250324db3 Author: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Date: Wed Dec 16 17:12:21 2020 -0800 HID: core: detect and skip invalid inputs to snto32() [ Upstream commit a0312af1f94d13800e63a7d0a66e563582e39aec ] Prevent invalid (0, 0) inputs to hid-core's snto32() function. Maybe it is just the dummy device here that is causing this, but there are hundreds of calls to snto32(0, 0). Having n (bits count) of 0 is causing the current UBSAN trap with a shift value of 0xffffffff (-1, or n - 1 in this function). Either of the value to shift being 0 or the bits count being 0 can be handled by just returning 0 to the caller, avoiding the following complex shift + OR operations: return value & (1 << (n - 1)) ? value | (~0U << n) : value; Fixes: dde5845a529f ("[PATCH] Generic HID layer - code split") Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Reported-by: syzbot+1e911ad71dd4ea72e04a@xxxxxxxxxxxxxxxxxxxxxxxxx Cc: Jiri Kosina <jikos@xxxxxxxxxx> Cc: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> Cc: linux-input@xxxxxxxxxxxxxxx Signed-off-by: Jiri Kosina <jkosina@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 8a8b2b982f83c..097cb1ee31268 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1307,6 +1307,9 @@ EXPORT_SYMBOL_GPL(hid_open_report); static s32 snto32(__u32 value, unsigned n) { + if (!value || !n) + return 0; + switch (n) { case 8: return ((__s8)value); case 16: return ((__s16)value);