Fedor Pchelkin [off-list ref] writes:

It is possible that skb is freed in ath9k_htc_rx_msg(), then
usb_submit_urb() fails and we try to free skb again. It causes
use-after-free bug. Moreover, if alloc_skb() fails, urb->context becomes
NULL but rx_buf is not freed and there can be a memory leak.

The patch removes unnecessary nskb and makes skb processing more clear: it
is supposed that ath9k_htc_rx_msg() either frees old skb or passes its
managing to another callback function.

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

Fixes: 3deff76095c4 ("ath9k_htc: Increase URB count for REG_IN pipe")
Signed-off-by: Fedor Pchelkin <redacted>
Signed-off-by: Alexey Khoroshilov <redacted>

Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>