[PATCH] wifi: carl9170: reject mismatched command response lengths

[Yousef Alhouseen <alhouseenyousef@gmail.com>]

The firmware response length is controlled by the USB device. Although
carl9170_cmd_callback() detects when it differs from the output buffer
length, the function falls through and copies the entire response into
that buffer. Callers commonly provide stack objects, so a malformed
response can overwrite the kernel stack.

Return after scheduling device recovery. This also preserves the stated
behavior of leaving the command incomplete so that its waiter times out
and clears the pending output buffer.

Fixes: a84fab3cbfdc ("carl9170: 802.11 rx/tx processing and usb backend")
Reported-by: syzbot+5c1ca6ccaa1215781cac@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5c1ca6ccaa1215781cac
Cc: stable@vger.kernel.org
Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>
---
 drivers/net/wireless/ath/carl9170/rx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/wireless/ath/carl9170/rx.c b/drivers/net/wireless/ath/carl9170/rx.c
index 6833430130f4..ea3f435fb64c 100644
--- a/drivers/net/wireless/ath/carl9170/rx.c
+++ b/drivers/net/wireless/ath/carl9170/rx.c
@@ -145,6 +145,7 @@ static void carl9170_cmd_callback(struct ar9170 *ar, u32 len, void *buffer)
 		 * and we get a stack trace from there.
 		 */
 		carl9170_restart(ar, CARL9170_RR_INVALID_RSP);
+		return;
 	}
 
 	spin_lock(&ar->cmd_lock);
-- 
2.54.0