[ 3.5.y.z extended stable ] Patch "ath9k: fix stale pointers potentially causing access to" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    ath9k: fix stale pointers potentially causing access to

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 04738e968780613ff06e2659410a883ca1060673 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd at openwrt.org>
Date: Fri, 26 Oct 2012 00:31:11 +0200
Subject: [PATCH] ath9k: fix stale pointers potentially causing access to
 free'd skbs
X-Extended-Stable: 3.5

commit 8c6e30936a7893a85f6222084f0f26aceb81137a upstream.

bf->bf_next is only while buffers are chained as part of an A-MPDU
in the tx queue. When a tid queue is flushed (e.g. on tearing down
an aggregation session), frames can be enqueued again as normal
transmission, without bf_next being cleared. This can lead to the
old pointer being dereferenced again later.

This patch might fix crashes and "Failed to stop TX DMA!" messages.

Signed-off-by: Felix Fietkau <nbd at openwrt.org>
Signed-off-by: John W. Linville <linville at tuxdriver.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/net/wireless/ath/ath9k/xmit.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index b78773b..11f252f 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -337,6 +337,7 @@ static struct ath_buf *ath_tx_get_buffer(struct ath_softc *sc)
 	}

 	bf = list_first_entry(&sc->tx.txbuf, struct ath_buf, list);
+	bf->bf_next = NULL;
 	list_del(&bf->list);

 	spin_unlock_bh(&sc->tx.txbuflock);
@@ -1760,6 +1761,7 @@ static void ath_tx_send_normal(struct ath_softc *sc, struct ath_txq *txq,
 	list_add_tail(&bf->list, &bf_head);
 	bf->bf_state.bf_type = 0;

+	bf->bf_next = NULL;
 	bf->bf_lastbf = bf;
 	ath_tx_fill_desc(sc, bf, txq, fi->framelen);
 	ath_tx_txqaddbuf(sc, txq, &bf_head, false);
--
1.7.9.5