[PATCH] rndis_wlan: potential buffer overflow in rndis_wlan_auth_indication()

[PATCH] rndis_wlan: potential buffer overflow in rndis_wlan_auth_indication()

[Dan Carpenter]

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@oracle.com>

diff --git a/drivers/net/wireless/rndis_wlan.c b/drivers/net/wireless/rndis_wlan.c
index 9935bd09db1f..d4947e3a909e 100644
--- a/drivers/net/wireless/rndis_wlan.c
+++ b/drivers/net/wireless/rndis_wlan.c
@@ -2928,6 +2928,8 @@ static void rndis_wlan_auth_indication(struct usbnet *usbdev,
 
 	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;

Re: rndis_wlan: potential buffer overflow in rndis_wlan_auth_indication()

[Kalle Valo]

Dan Carpenter <dan.carpenter@oracle.com> wrote:

> 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@oracle.com>
> 
> diff --git a/drivers/net/wireless/rndis_wlan.c b/drivers/net/wireless/rndis_wlan.c
> index 9935bd09db1f..d4947e3a909e 100644
> --- a/drivers/net/wireless/rndis_wlan.c
> +++ b/drivers/net/wireless/rndis_wlan.c
> @@ -2928,6 +2928,8 @@ static void rndis_wlan_auth_indication(struct usbnet *usbdev,
>  
>  	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;

Patch applied to wireless-drivers-next.git, thanks.

ae636fb15548 rndis_wlan: potential buffer overflow in rndis_wlan_auth_indication()

-- 
https://patchwork.kernel.org/patch/10448061/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches