[PATCH] mac80211: fix txq null pointer dereference

* [PATCH] mac80211: fix txq null pointer dereference
@ 2019-09-27  2:03 Miaoqing Pan
  2019-09-27  6:17 ` Toke Høiland-Jørgensen
  0 siblings, 1 reply; 2+ messages in thread
From: Miaoqing Pan @ 2019-09-27  2:03 UTC (permalink / raw)
  To: johannes; +Cc: linux-wireless, ath10k, Miaoqing Pan

If the interface type is P2P_DEVICE or NAN, read the file of
'/sys/kernel/debug/ieee80211/phyx/netdev:wlanx/aqm' will get a
NULL pointer dereference. As for those interface type, the
pointer sdata->vif.txq is NULL.

Unable to handle kernel NULL pointer dereference at virtual address 00000011
CPU: 1 PID: 30936 Comm: cat Not tainted 4.14.104 #1
task: ffffffc0337e4880 task.stack: ffffff800cd20000
PC is at ieee80211_if_fmt_aqm+0x34/0xa0 [mac80211]
LR is at ieee80211_if_fmt_aqm+0x34/0xa0 [mac80211]
pc : [<ffffff8000b7cd00>] lr : [<ffffff8000b7cd00>] pstate: 60000145
sp : ffffff800cd23bb0
x29: ffffff800cd23c00 x28: ffffffc0337e4880
x27: ffffff8008a04000 x26: 0000000000000003
x25: 000000000000018e x24: ffffff80090f9d30
x23: ffffffc034b62000 x22: 0000000000000000
x21: ffffffc0335008e0 x20: ffffff800cd23c10
x19: 00000000000000c8 x18: 0000000000000000
x17: 0000000000000000 x16: ffffff80081ef454
x15: 0000000000000000 x14: 00000000f45c1d27
x13: 00000000ffab6710 x12: 0000000000000003
x11: 0000000000000006 x10: 0000000000000000
x9 : 0000000000000001 x8 : ffffffc0337e4880
x7 : 0000000000000003 x6 : 00000000f4498000
x5 : 0000000000000000 x4 : ffffff8000b7cccc
x3 : ffffff800cd23e80 x2 : 00000000000000c8
x1 : ffffff800cd23c10 x0 : ffffffc0335008e0
Process cat (pid: 30936, stack limit = 0xffffff800cd20000)
[Call trace:
Exception stack(0xffffff800cd23a70 to 0xffffff800cd23bb0)
3a60:                                   ffffffc0335008e0 ffffff800cd23c10
3a80: 00000000000000c8 ffffff800cd23e80 ffffff8000b7cccc 0000000000000000
3aa0: 00000000f4498000 0000000000000003 ffffffc0337e4880 0000000000000001
3ac0: 0000000000000000 0000000000000006 0000000000000003 00000000ffab6710
3ae0: 00000000f45c1d27 0000000000000000 ffffff80081ef454 0000000000000000
3b00: 0000000000000000 00000000000000c8 ffffff800cd23c10 ffffffc0335008e0
3b20: 0000000000000000 ffffffc034b62000 ffffff80090f9d30 000000000000018e
3b40: 0000000000000003 ffffff8008a04000 ffffffc0337e4880 ffffff800cd23c00
3b60: ffffff8000b7cd00 ffffff800cd23bb0 ffffff8000b7cd00 0000000060000145
3b80: ffffff800cd23ba0 ffffff80088e16e4 0000007fffffffff ffffff800cd23c40
3ba0: ffffff800cd23c00 ffffff8000b7cd00
[<ffffff8000b7cd00>] ieee80211_if_fmt_aqm+0x34/0xa0 [mac80211]
[<ffffff8000b7c414>] ieee80211_if_read+0x60/0xbc [mac80211]
[<ffffff8000b7ccc4>] ieee80211_if_read_aqm+0x28/0x30 [mac80211]
[<ffffff80082eff94>] full_proxy_read+0x2c/0x48
[<ffffff80081eef00>] __vfs_read+0x2c/0xd4
[<ffffff80081ef084>] vfs_read+0x8c/0x108
[<ffffff80081ef494>] SyS_read+0x40/0x7c

Tested HW: QCA9984
Tested FW: 10.4-3.10-00047

Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
---
 net/mac80211/debugfs_netdev.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index b1438fd..64b544a 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -487,9 +487,14 @@ static ssize_t ieee80211_if_fmt_aqm(
 	const struct ieee80211_sub_if_data *sdata, char *buf, int buflen)
 {
 	struct ieee80211_local *local = sdata->local;
-	struct txq_info *txqi = to_txq_info(sdata->vif.txq);
+	struct txq_info *txqi;
 	int len;
 
+	if (!sdata->vif.txq)
+		return 0;
+
+	txqi = to_txq_info(sdata->vif.txq);
+
 	spin_lock_bh(&local->fq.lock);
 	rcu_read_lock();
 
@@ -658,7 +663,9 @@ static void add_common_files(struct ieee80211_sub_if_data *sdata)
 	DEBUGFS_ADD(rc_rateidx_vht_mcs_mask_5ghz);
 	DEBUGFS_ADD(hw_queues);
 
-	if (sdata->local->ops->wake_tx_queue)
+	if (sdata->local->ops->wake_tx_queue &&
+	    sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
+	    sdata->vif.type != NL80211_IFTYPE_NAN)
 		DEBUGFS_ADD(aqm);
 }
 
-- 
1.9.1


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