netdev - [PATCH] sr9700: sanity check for packet length

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Message-Id: <20220217131044.26983-1-oneukum@suse.com>
Date:   Thu, 17 Feb 2022 14:10:44 +0100
From:   Oliver Neukum <oneukum@...e.com>
To:     davem@...emloft.net, kuba@...nel.org, grundler@...omium.org,
        andrew@...n.ch, jgg@...pe.ca, linux-usb@...r.kernel.org,
        arnd@...db.de, netdev@...r.kernel.org
Cc:     Oliver Neukum <oneukum@...e.com>
Subject: [PATCH] sr9700: sanity check for packet length

A malicious device can leak heap data to user space
providing bogus frame lengths. Introduce a sanity check.

Signed-off-by: Oliver Neukum <oneukum@...e.com>
---
 drivers/net/usb/sr9700.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c
index b658510cc9a4..5a53e63d33a6 100644
--- a/drivers/net/usb/sr9700.c
+++ b/drivers/net/usb/sr9700.c
@@ -413,7 +413,7 @@ static int sr9700_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 		/* ignore the CRC length */
 		len = (skb->data[1] | (skb->data[2] << 8)) - 4;
 
-		if (len > ETH_FRAME_LEN)
+		if (len > ETH_FRAME_LEN || len > skb->len)
 			return 0;
 
 		/* the last packet of current skb */
-- 
2.34.1