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From:   trix@redhat.com
To:     kvalo@codeaurora.org, davem@davemloft.net, kuba@kernel.org,
        natechancellor@gmail.com, ndesaulniers@google.com,
        mkenna@codeaurora.org, vnaralas@codeaurora.org,
        rmanohar@codeaurora.org, john@phrozen.org
Cc:     ath11k@lists.infradead.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com, Tom Rix <trix@redhat.com>
Subject: [PATCH] ath11k: fix a double free and a memory leak
Date:   Sun,  6 Sep 2020 14:26:25 -0700
Message-Id: <20200906212625.17059-1-trix@redhat.com>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

From: Tom Rix <trix@redhat.com>

clang static analyzer reports this problem

mac.c:6204:2: warning: Attempt to free released memory
        kfree(ar->mac.sbands[NL80211_BAND_2GHZ].channels);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The channels pointer is allocated in ath11k_mac_setup_channels_rates()
When it fails midway, it cleans up the memory it has already allocated.
So the error handling needs to skip freeing the memory.

There is a second problem.
ath11k_mac_setup_channels_rates(), allocates 3 channels. err_free
misses releasing ar->mac.sbands[NL80211_BAND_6GHZ].channels

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/net/wireless/ath/ath11k/mac.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index f4a085baff38..f1a964b01a83 100644
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -6089,7 +6089,7 @@ static int __ath11k_mac_register(struct ath11k *ar)
 	ret = ath11k_mac_setup_channels_rates(ar,
 					      cap->supported_bands);
 	if (ret)
-		goto err_free;
+		goto err;
 
 	ath11k_mac_setup_ht_vht_cap(ar, cap, &ht_cap);
 	ath11k_mac_setup_he_cap(ar, cap);
@@ -6203,7 +6203,8 @@ static int __ath11k_mac_register(struct ath11k *ar)
 err_free:
 	kfree(ar->mac.sbands[NL80211_BAND_2GHZ].channels);
 	kfree(ar->mac.sbands[NL80211_BAND_5GHZ].channels);
-
+	kfree(ar->mac.sbands[NL80211_BAND_6GHZ].channels);
+err:
 	SET_IEEE80211_DEV(ar->hw, NULL);
 	return ret;
 }
-- 
2.18.1