[PATCH] ath9k: Fix potential out of bounds in ath9k_htc_txcompletion_cb()

* [PATCH] ath9k: Fix potential out of bounds in ath9k_htc_txcompletion_cb()
@ 2020-08-13 14:12 Dan Carpenter
  2020-08-17 10:24 ` Kalle Valo
  0 siblings, 1 reply; 2+ messages in thread
From: Dan Carpenter @ 2020-08-13 14:12 UTC (permalink / raw)
  To: QCA ath9k Development
  Cc: Kalle Valo, Jakub Kicinski, Vasanthakumar Thiagarajan,
	John W. Linville, Senthil Balasubramanian, Sujith,
	linux-wireless, kernel-janitors

The value of "htc_hdr->endpoint_id" comes from skb->data so Smatch marks
it as untrusted so we have to check it before using it as an array
offset.

This is similar to a bug that syzkaller found in commit e4ff08a4d727
("ath9k: Fix use-after-free Write in ath9k_htc_rx_msg") so it is
probably a real issue.

Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/net/wireless/ath/ath9k/htc_hst.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index d2e062eaf561..510e61e97dbc 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -339,6 +339,8 @@ void ath9k_htc_txcompletion_cb(struct htc_target *htc_handle,
 
 	if (skb) {
 		htc_hdr = (struct htc_frame_hdr *) skb->data;
+		if (htc_hdr->endpoint_id >= ARRAY_SIZE(htc_handle->endpoint))
+			goto ret;
 		endpoint = &htc_handle->endpoint[htc_hdr->endpoint_id];
 		skb_pull(skb, sizeof(struct htc_frame_hdr));
 
-- 
2.28.0

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