Subject: [PATCH AUTOSEL 4.14 2/7] sr9700: sanity check for packet length

From: Sasha Levin <[email-masked]>
Date: Tue, 1 Mar 2022 15:21:23 -0500

From: Oliver Neukum <[email-masked]>

[ Upstream commit e9da0b56fe27206b49f39805f7dcda8a89379062 ]

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

Signed-off-by: Oliver Neukum <[email-masked]>
Reviewed-by: Grant Grundler <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 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 2d316c1b851b2..a97dd62b9d54b 100644
--- a/drivers/net/usb/sr9700.c
+++ b/drivers/net/usb/sr9700.c
@@ -410,7 +410,7 @@ 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