[PATCH 3.16 010/328] rndis_wlan: potential buffer overflow in rndis_wlan_auth_indication()

From: Ben Hutchings
Date: Sun Dec 09 2018 - 17:26:32 EST

3.16.62-rc1 review patch. If anyone has any objections, please let me know.


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit ae636fb1554833ee5133ca47bf4b2791b6739c52 upstream.

This is a static checker fix, not something I have tested. The issue
is that on the second iteration through the loop, we jump forward by
le32_to_cpu(auth_req->length) bytes. The problem is that if the length
is more than "buflen" then we end up with a negative "buflen". A
negative buflen is type promoted to a high positive value and the loop
continues but it's accessing beyond the end of the buffer.

I believe the "auth_req->length" comes from the firmware and if the
firmware is malicious or buggy, you're already toasted so the impact of
this bug is probably not very severe.

Fixes: 030645aceb3d ("rndis_wlan: handle 802.11 indications from device")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/net/wireless/rndis_wlan.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/net/wireless/rndis_wlan.c
+++ b/drivers/net/wireless/rndis_wlan.c
@@ -2917,6 +2917,8 @@ static void rndis_wlan_auth_indication(s

while (buflen >= sizeof(*auth_req)) {
auth_req = (void *)buf;
+ if (buflen < le32_to_cpu(auth_req->length))
+ return;
type = "unknown";
flags = le32_to_cpu(auth_req->flags);
pairwise_error = false;