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| author | One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> | 2016-01-05 11:51:25 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-01-06 01:25:01 -0500 |
| commit | 60aa3b080a3d2b408af2ca114edb3efc84ad1838 (patch) | |
| tree | 6150db6b5626e1994ff23db0ac66a255556b83bc | |
| parent | 55795ef5469290f89f04e12e662ded604909e462 (diff) | |
| download | linux-60aa3b080a3d2b408af2ca114edb3efc84ad1838.tar.bz2 | |
6pack: fix free memory scribbles
commit acf673a3187edf72068ee2f92f4dc47d66baed47 fixed a user triggerable free
memory scribble but in doing so replaced it with a different one that allows
the user to control the data and scribble even more.
sixpack_close is called by the tty layer in tty context. The tty context is
protected by sp_get() and sp_put(). However network layer activity via
sp_xmit() is not protected this way. We must therefore stop the queue
otherwise the user gets to dump a buffer mostly of their choice into freed
kernel pages.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/hamradio/6pack.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index 9f0b1c342b77..5a1e98547031 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -683,6 +683,12 @@ static void sixpack_close(struct tty_struct *tty) if (!atomic_dec_and_test(&sp->refcnt)) down(&sp->dead_sem); + /* We must stop the queue to avoid potentially scribbling + * on the free buffers. The sp->dead_sem is not sufficient + * to protect us from sp->xbuff access. + */ + netif_stop_queue(sp->dev); + del_timer_sync(&sp->tx_t); del_timer_sync(&sp->resync_t); |