Re: [syzbot] [PATCH] usb: fix slab-out-of-bounds Read in cougar_report_fixup

[syzbot <syzbot+24c0361074799d02c452@syzkaller.appspotmail.com>]

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***

Subject: [PATCH] usb: fix slab-out-of-bounds Read in cougar_report_fixup
Author: cam.alvarez.i@gmail.com

#syz test
report_fixup for the Cougar 500k Gaming Keyboard was not verifying
that the report descriptor size was correct before accessing it

Signed-off-by: Camila Alvarez <cam.alvarez.i@gmail.com>
---
 drivers/hid/hid-cougar.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-cougar.c b/drivers/hid/hid-cougar.c
index cb8bd8aae15b..0fa785f52707 100644
--- a/drivers/hid/hid-cougar.c
+++ b/drivers/hid/hid-cougar.c
@@ -106,7 +106,7 @@ static void cougar_fix_g6_mapping(void)
 static __u8 *cougar_report_fixup(struct hid_device *hdev, __u8 *rdesc,
 				 unsigned int *rsize)
 {
-	if (rdesc[2] == 0x09 && rdesc[3] == 0x02 &&
+	if (*rsize >= 117 && rdesc[2] == 0x09 && rdesc[3] == 0x02 &&
 	    (rdesc[115] | rdesc[116] << 8) >= HID_MAX_USAGES) {
 		hid_info(hdev,
 			"usage count exceeds max: fixing up report descriptor\n");
-- 
2.34.1