[PATCH] wifi: ath9k: add range check for epid in htc_issue_send()

[Aleksandr Nesterenko <alexandernesterenko837@gmail.com>]

The fix for CVE-2024-53156 (commit 8619593634cb ("wifi: ath9k: add
range check for conn_rsp_epid in htc_connect_service()")) added a
bounds check for conn_rsp_epid in htc_connect_service() to prevent
out-of-bounds array access. However, htc_issue_send() accesses
target->endpoint[epid] directly without validating the epid parameter.

While htc_connect_service() now validates the endpoint ID before storing
it, htc_issue_send() can still receive invalid epid values from callers
such as htc_send() and htc_send_epid(). This provides defense-in-depth
against out-of-bounds access.

Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Signed-off-by: Aleksandr Nesterenko <alexandernesterenko837@gmail.com>
---
 drivers/net/wireless/ath/ath9k/htc_hst.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index 00dc97ac53b9..7821a31c0abb 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -23,9 +23,16 @@ static int htc_issue_send(struct htc_target *target, struct sk_buff* skb,
 
 {
 	struct htc_frame_hdr *hdr;
-	struct htc_endpoint *endpoint = &target->endpoint[epid];
+	struct htc_endpoint *endpoint;
 	int status;
 
+	if (epid >= ENDPOINT_MAX) {
+		kfree_skb(skb);
+		return -EINVAL;
+	}
+
+	endpoint = &target->endpoint[epid];
+
 	hdr = skb_push(skb, sizeof(struct htc_frame_hdr));
 	hdr->endpoint_id = epid;
 	hdr->flags = flags;
-- 
2.34.1