From 88a4a2e8ceccdb548766bcf0ac256738796cb6fa Mon Sep 17 00:00:00 2001 From: Alan Date: Wed, 6 Jan 2016 14:55:02 +0000 Subject: [PATCH] mkiss: fix scribble on freed memory commit c53d2122e3b634fb49ca1ff4bb53c6d8d5966da3 fixed a user triggerable scribble on free memory but added a new one which allows the user to scribble even more and user controlled data into freed space. As with 6pack we need to halt the queue before we free the buffers, because the transmit logic is not protected by the semaphore. Signed-off-by: Alan Cox Signed-off-by: David S. Miller --- drivers/net/hamradio/mkiss.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c index 0b72b9de52072..85828f1534454 100644 --- a/drivers/net/hamradio/mkiss.c +++ b/drivers/net/hamradio/mkiss.c @@ -797,6 +797,11 @@ static void mkiss_close(struct tty_struct *tty) */ if (!atomic_dec_and_test(&ax->refcnt)) down(&ax->dead_sem); + /* + * Halt the transmit queue so that a new transmit cannot scribble + * on our buffers + */ + netif_stop_queue(ax->dev); /* Free all AX25 frame buffers. */ kfree(ax->rbuff); -- 2.39.5