From cf8ce1ea61b75712a154c93e40f2a5af2e4dd997 Mon Sep 17 00:00:00 2001 From: Miaoqing Pan Date: Tue, 27 Jun 2017 17:31:49 +0300 Subject: [PATCH] ath9k: fix tx99 use after free One scenario that could lead to UAF is two threads writing simultaneously to the "tx99" debug file. One of them would set the "start" value to true and follow to ath9k_tx99_init(). Inside the function it would set the sc->tx99_state to true after allocating sc->tx99skb. Then, the other thread would execute write_file_tx99() and call ath9k_tx99_deinit(). sc->tx99_state would be freed. After that, the first thread would continue inside ath9k_tx99_init() and call r = ath9k_tx99_send(sc, sc->tx99_skb, &txctl); that would make use of the freed sc->tx99_skb memory. Cc: Signed-off-by: Miaoqing Pan Signed-off-by: Kalle Valo --- drivers/net/wireless/ath/ath9k/tx99.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/net/wireless/ath/ath9k/tx99.c b/drivers/net/wireless/ath/ath9k/tx99.c index a866cbda0799..49ed1afb913c 100644 --- a/drivers/net/wireless/ath/ath9k/tx99.c +++ b/drivers/net/wireless/ath/ath9k/tx99.c @@ -189,22 +189,27 @@ static ssize_t write_file_tx99(struct file *file, const char __user *user_buf, if (strtobool(buf, &start)) return -EINVAL; + mutex_lock(&sc->mutex); + if (start == sc->tx99_state) { if (!start) - return count; + goto out; ath_dbg(common, XMIT, "Resetting TX99\n"); ath9k_tx99_deinit(sc); } if (!start) { ath9k_tx99_deinit(sc); - return count; + goto out; } r = ath9k_tx99_init(sc); - if (r) + if (r) { + mutex_unlock(&sc->mutex); return r; - + } +out: + mutex_unlock(&sc->mutex); return count; } -- 2.20.1