From: Randy Dunlap rdunlap@infradead.org
[ 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@infradead.org Reported-by: syzbot+1e911ad71dd4ea72e04a@syzkaller.appspotmail.com Cc: Jiri Kosina jikos@kernel.org Cc: Benjamin Tissoires benjamin.tissoires@redhat.com Cc: linux-input@vger.kernel.org Signed-off-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hid/hid-core.c | 3 +++ 1 file changed, 3 insertions(+)
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);