* [PATCH 5.10 274/663] HID: core: detect and skip invalid inputs to snto32()
[not found] <20210301161141.760350206@linuxfoundation.org>
@ 2021-03-01 16:08 ` Greg Kroah-Hartman
0 siblings, 0 replies; only message in thread
From: Greg Kroah-Hartman @ 2021-03-01 16:08 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Randy Dunlap,
syzbot+1e911ad71dd4ea72e04a, Jiri Kosina, Benjamin Tissoires,
linux-input, Jiri Kosina, Sasha Levin
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);
--
2.27.0
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