[PATCH] HID: core: s32ton always be 0 when n>=32

[Pei Xiao]

s32ton always be 0 when n>=32,add check n.

Reported-by: syzbot+3fa2af55f15bd21cada9@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=3fa2af55f15bd21cada9
Fixes: c653ffc28340 ("HID: stop exporting hid_snto32()")
Signed-off-by: Pei Xiao <xiaopei01@xxxxxxxxxx>
---
 drivers/hid/hid-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 81d6c734c8bc..ead1d338fa58 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -66,8 +66,11 @@ static s32 snto32(__u32 value, unsigned int n)
 
 static u32 s32ton(__s32 value, unsigned int n)
 {
-	s32 a = value >> (n - 1);
+	s32 a;
 
+	if (n >= 32)
+		return value;
+	a = value >> (n - 1);
 	if (a && a != -1)
 		return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
 	return value & ((1 << n) - 1);
-- 
2.34.1