linux-kernel - [PATCH 3.4 032/107] mac80211: clear subdir

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Message-Id: <1458115601-5762-32-git-send-email-lizf@kernel.org>
Date:	Wed, 16 Mar 2016 16:05:26 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Tom Hughes <tom@...pton.nu>,
	Johannes Berg <johannes.berg@...el.com>,
	Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 032/107] mac80211: clear subdir_stations when removing debugfs

From: Tom Hughes <tom@...pton.nu>

3.4.111-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit 4479004e6409087d1b4986881dc98c6c15dffb28 upstream.

If we don't do this, and we then fail to recreate the debugfs
directory during a mode change, then we will fail later trying
to add stations to this now bogus directory:

BUG: unable to handle kernel NULL pointer dereference at 0000006c
IP: [<c0a92202>] mutex_lock+0x12/0x30
Call Trace:
[<c0678ab4>] start_creating+0x44/0xc0
[<c0679203>] debugfs_create_dir+0x13/0xf0
[<f8a938ae>] ieee80211_sta_debugfs_add+0x6e/0x490 [mac80211]

Signed-off-by: Tom Hughes <tom@...pton.nu>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@...wei.com>
---
 net/mac80211/debugfs_netdev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index d5404cc..fa4a689 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -700,6 +700,7 @@ void ieee80211_debugfs_remove_netdev(struct ieee80211_sub_if_data *sdata)
 
 	debugfs_remove_recursive(sdata->debugfs.dir);
 	sdata->debugfs.dir = NULL;
+	sdata->debugfs.subdir_stations = NULL;
 }
 
 void ieee80211_debugfs_rename_netdev(struct ieee80211_sub_if_data *sdata)
-- 
1.9.1