From b01c9e327249e4995e5b5b6cebec14166db9c1e7 Mon Sep 17 00:00:00 2001
From: Stanislaw Gruszka <sgruszka@redhat.com>
Date: Wed, 10 May 2017 10:54:54 +0200
Subject: [PATCH] ath9k: check ah->curchan when updating tx power
Git-commit: b01c9e327249e4995e5b5b6cebec14166db9c1e7
Patch-mainline: v4.13-rc1
References: FATE#326906
When driver fail to reset card ah->curchan value stay NULL. When
later driver try to update tx power it oops by using ah->curchan
(calltrace is shown below).
This problem were reported at various places and for some it was
fixed by making ath9k_hw_chip_reset() do not fail. I have this bug
report on some oldish RHEL kernel with AR9285, however it's hard to
debug where reset fail when kernel OOPS, so I think this patch
should be applied. Hopefully ah->curchan is not used unconditionally
on other places until is initialized on ath9k_config().
Ath: phy0: Chip reset failed
Ath: phy0: Unable to reset hardware; reset status -22 (freq 2412 MHz)
Bug: unable to handle kernel NULL pointer dereference at (null)
Ip: [<f8a35585>] ath9k_hw_set_txpowerlimit+0x25/0x80 [ath9k_hw]
Oops: 0000 [#1] SMP
<snip>
Call Trace:
[<f8aac1aa>] ? ath9k_cmn_update_txpow+0x1a/0x30 [ath9k_common]
[<f8cf4f4e>] ? ath_complete_reset+0x4e/0x130 [ath9k]
[<f8cf54d7>] ? ath9k_start+0x127/0x1e0 [ath9k]
[<f8c2e52f>] ? ieee80211_do_open+0x30f/0x910 [mac80211]
[<c07bd96d>] ? dev_open+0x8d/0xf0
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/wireless/ath/ath9k/common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/ath/ath9k/common.c b/drivers/net/wireless/ath/ath9k/common.c
index b80e08b13b74..eea2f7f23a2a 100644
--- a/drivers/net/wireless/ath/ath9k/common.c
+++ b/drivers/net/wireless/ath/ath9k/common.c
@@ -368,7 +368,7 @@ void ath9k_cmn_update_txpow(struct ath_hw *ah, u16 cur_txpow,
{
struct ath_regulatory *reg = ath9k_hw_regulatory(ah);
- if (reg->power_limit != new_txpow)
+ if (ah->curchan && reg->power_limit != new_txpow)
ath9k_hw_set_txpowerlimit(ah, new_txpow, false);
/* read back in case value is clamped */
--
2.19.2