linux-kernel - [PATCH] usb: fix slab-out-of-bounds Read in cougar_report

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Message-Id: <20240730234242.256598-1-cam.alvarez.i@gmail.com>
Date: Tue, 30 Jul 2024 19:42:43 -0400
From: Camila Alvarez <cam.alvarez.i@...il.com>
To: Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <bentiss@...nel.org>
Cc: linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Camila Alvarez <cam.alvarez.i@...il.com>,
	syzbot+24c0361074799d02c452@...kaller.appspotmail.com
Subject: [PATCH] usb: fix slab-out-of-bounds Read in cougar_report_fixup

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

Reported-by: syzbot+24c0361074799d02c452@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=24c0361074799d02c452
Signed-off-by: Camila Alvarez <cam.alvarez.i@...il.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