linux-kernel - [PATCH] ath: dfs_pattern_detector: Fix possible null-pointer dereference in channel_detector

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Message-Id: <20210805153854.154066-1-islituo@gmail.com>
Date:   Thu,  5 Aug 2021 08:38:53 -0700
From:   Tuo Li <islituo@...il.com>
To:     kvalo@...eaurora.org, davem@...emloft.net, kuba@...nel.org
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, baijiaju1990@...il.com,
        Tuo Li <islituo@...il.com>, TOTE Robot <oslab@...nghua.edu.cn>
Subject: [PATCH] ath: dfs_pattern_detector: Fix possible null-pointer dereference in channel_detector_create()

kzalloc() is used to allocate memory for cd->detectors, and if it fails,
channel_detector_exit() behind the label fail will be called:
  channel_detector_exit(dpd, cd);

In channel_detector_exit(), cd->detectors is dereferenced through:
  struct pri_detector *de = cd->detectors[i];

To fix this possible null-pointer dereference, check cd->detectors before 
the for loop to dereference cd->detectors. 

Reported-by: TOTE Robot <oslab@...nghua.edu.cn>
Signed-off-by: Tuo Li <islituo@...il.com>
---
 drivers/net/wireless/ath/dfs_pattern_detector.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/ath/dfs_pattern_detector.c b/drivers/net/wireless/ath/dfs_pattern_detector.c
index 80390495ea25..75cb53a3ec15 100644
--- a/drivers/net/wireless/ath/dfs_pattern_detector.c
+++ b/drivers/net/wireless/ath/dfs_pattern_detector.c
@@ -183,10 +183,12 @@ static void channel_detector_exit(struct dfs_pattern_detector *dpd,
 	if (cd == NULL)
 		return;
 	list_del(&cd->head);
-	for (i = 0; i < dpd->num_radar_types; i++) {
-		struct pri_detector *de = cd->detectors[i];
-		if (de != NULL)
-			de->exit(de);
+	if (cd->detectors) {
+		for (i = 0; i < dpd->num_radar_types; i++) {
+			struct pri_detector *de = cd->detectors[i];
+			if (de != NULL)
+				de->exit(de);
+		}
 	}
 	kfree(cd->detectors);
 	kfree(cd);
-- 
2.25.1