linux-kernel - [PATCH V2] cfg80211: Fix possible memory leak in function cfg80211_bss

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Message-Id: <20210628132334.851095-1-phind.uet@gmail.com>
Date:   Mon, 28 Jun 2021 21:23:34 +0800
From:   Nguyen Dinh Phi <phind.uet@...il.com>
To:     johannes@...solutions.net, davem@...emloft.net, kuba@...nel.org
Cc:     Nguyen Dinh Phi <phind.uet@...il.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: [PATCH V2] cfg80211: Fix possible memory leak in function cfg80211_bss_update

When we exceed the limit of BSS entries, this function will free the
new entry, however, at this time, it is the last door to access the
inputed ies, so these ies will be unreferenced objects and cause memory
leak.
Therefore we should free its ies before deallocating the new entry, beside
of dropping it from hidden_list.

Signed-off-by: Nguyen Dinh Phi <phind.uet@...il.com>
---
V2:	- Add subsystem to the subject line.
	- Use bss_ref_put function for better clean-up dynamically allocated
	cfg80211_internal_bss objects. It helps to clean relative hidden_bss.

 net/wireless/scan.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index f03c7ac8e184..7897b1478c3c 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1754,16 +1754,14 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
 			 * be grouped with this beacon for updates ...
 			 */
 			if (!cfg80211_combine_bsses(rdev, new)) {
-				kfree(new);
+				bss_ref_put(rdev, new);
 				goto drop;
 			}
 		}

 		if (rdev->bss_entries >= bss_entries_limit &&
 		    !cfg80211_bss_expire_oldest(rdev)) {
-			if (!list_empty(&new->hidden_list))
-				list_del(&new->hidden_list);
-			kfree(new);
+			bss_ref_put(rdev, new);
 			goto drop;
 		}

--
2.25.1