linux-kernel - [PATCH] net: wireless: ath9k: avoid possible NULL pointer dereference

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Date:	Fri, 29 Nov 2013 18:06:46 +0100
From:	Michal Nazarewicz <mpn@...gle.com>
To:	"John W. Linville" <linville@...driver.com>
Cc:	linux-wireless@...r.kernel.org, ath9k-devel@...ts.ath9k.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] net: wireless: ath9k: avoid possible NULL pointer dereference

From: Michal Nazarewicz <mina86@...a86.com>

Code in ath9k_hw_set_clockrate function indicates that ah->curchan
(and thus chan local variable) may be NULL.  If that is indeed the
case, IS_CHAN_HT40(chan) check has to be performed only in branch
where chan is not NULL.  Moving the code under already existing
if condition fixes this issue.

Signed-off-by: Michal Nazarewicz <mina86@...a86.com>
---
 drivers/net/wireless/ath/ath9k/hw.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 54b0415..8918035 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -146,10 +146,9 @@ static void ath9k_hw_set_clockrate(struct ath_hw *ah)
 	else
 		clockrate = ATH9K_CLOCK_RATE_5GHZ_OFDM;
 
-	if (IS_CHAN_HT40(chan))
-		clockrate *= 2;
-
-	if (ah->curchan) {
+	if (chan) {
+		if (IS_CHAN_HT40(chan))
+			clockrate *= 2;
 		if (IS_CHAN_HALF_RATE(chan))
 			clockrate /= 2;
 		if (IS_CHAN_QUARTER_RATE(chan))
-- 
1.8.4.1

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