wifi: ath9k: don't allow to overwrite ENDPOINT0 attributes

A bad USB device is able to construct a service connection response
message with target endpoint being ENDPOINT0 which is reserved for
HTC_CTRL_RSVD_SVC and should not be modified to be used for any other
services.

Reject such service connection responses.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Reported-by: syzbot+b68fbebe56d8362907e8@syzkaller.appspotmail.com
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230516150427.79469-1-pchelkin@ispras.ru

diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index fe62ff668f757b621ac773e457f5c42ce7073e20..99667aba289df0c9aeac94c15e7b1992db8907e0 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -114,7 +114,13 @@ static void htc_process_conn_rsp(struct htc_target *target,
 
        if (svc_rspmsg->status == HTC_SERVICE_SUCCESS) {
                epid = svc_rspmsg->endpoint_id;
-               if (epid < 0 || epid >= ENDPOINT_MAX)
+
+               /* Check that the received epid for the endpoint to attach
+                * a new service is valid. ENDPOINT0 can't be used here as it
+                * is already reserved for HTC_CTRL_RSVD_SVC service and thus
+                * should not be modified.
+                */
+               if (epid <= ENDPOINT0 || epid >= ENDPOINT_MAX)
                        return;
 
                service_id = be16_to_cpu(svc_rspmsg->service_id);