[PATCH 3.2 136/200] ath9k: protect tid->sched check
From: Ben Hutchings
Date: Sun Mar 30 2014 - 20:14:07 EST
3.2.56-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
commit 21f8aaee0c62708654988ce092838aa7df4d25d8 upstream.
We check tid->sched without a lock taken on ath_tx_aggr_sleep(). That
is race condition which can result of doing list_del(&tid->list) twice
(second time with poisoned list node) and cause crash like shown below:
[424271.637220] BUG: unable to handle kernel paging request at 00100104
[424271.637328] IP: [<f90fc072>] ath_tx_aggr_sleep+0x62/0xe0 [ath9k]
...
[424271.639953] Call Trace:
[424271.639998] [<f90f6900>] ? ath9k_get_survey+0x110/0x110 [ath9k]
[424271.640083] [<f90f6942>] ath9k_sta_notify+0x42/0x50 [ath9k]
[424271.640177] [<f809cfef>] sta_ps_start+0x8f/0x1c0 [mac80211]
[424271.640258] [<c10f730e>] ? free_compound_page+0x2e/0x40
[424271.640346] [<f809e915>] ieee80211_rx_handlers+0x9d5/0x2340 [mac80211]
[424271.640437] [<c112f048>] ? kmem_cache_free+0x1d8/0x1f0
[424271.640510] [<c1345a84>] ? kfree_skbmem+0x34/0x90
[424271.640578] [<c10fc23c>] ? put_page+0x2c/0x40
[424271.640640] [<c1345a84>] ? kfree_skbmem+0x34/0x90
[424271.640706] [<c1345a84>] ? kfree_skbmem+0x34/0x90
[424271.640787] [<f809dde3>] ? ieee80211_rx_handlers_result+0x73/0x1d0 [mac80211]
[424271.640897] [<f80a07a0>] ieee80211_prepare_and_rx_handle+0x520/0xad0 [mac80211]
[424271.641009] [<f809e22d>] ? ieee80211_rx_handlers+0x2ed/0x2340 [mac80211]
[424271.641104] [<c13846ce>] ? ip_output+0x7e/0xd0
[424271.641182] [<f80a1057>] ieee80211_rx+0x307/0x7c0 [mac80211]
[424271.641266] [<f90fa6ee>] ath_rx_tasklet+0x88e/0xf70 [ath9k]
[424271.641358] [<f80a0f2c>] ? ieee80211_rx+0x1dc/0x7c0 [mac80211]
[424271.641445] [<f90f82db>] ath9k_tasklet+0xcb/0x130 [ath9k]
Bug report:
https://bugzilla.kernel.org/show_bug.cgi?id=70551
Reported-and-tested-by: Max Sydorenko <maxim.stargazer@xxxxxxxxx>
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
[bwh: Backported to 3.2:
- Adjust context
- Use spin_unlock_bh() directly]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/net/wireless/ath/ath9k/xmit.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1176,14 +1176,16 @@ void ath_tx_aggr_sleep(struct ieee80211_
for (tidno = 0, tid = &an->tid[tidno];
tidno < WME_NUM_TID; tidno++, tid++) {
- if (!tid->sched)
- continue;
-
ac = tid->ac;
txq = ac->txq;
spin_lock_bh(&txq->axq_lock);
+ if (!tid->sched) {
+ spin_unlock_bh(&txq->axq_lock);
+ continue;
+ }
+
buffered = !skb_queue_empty(&tid->buf_q);
tid->sched = false;
--
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