linux-kernel - [PATCH AUTOSEL 4.14 120/127] apparmor: delete the dentry in aafs

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Message-Id: <20191122055544.3299-118-sashal@kernel.org>
Date:   Fri, 22 Nov 2019 00:55:37 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Chris Coulson <chris.coulson@...onical.com>,
        John Johansen <john.johansen@...onical.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-security-module@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 120/127] apparmor: delete the dentry in aafs_remove() to avoid a leak

From: Chris Coulson <chris.coulson@...onical.com>

[ Upstream commit 201218e4d3dfa1346e30997f48725acce3f26d01 ]

Although the apparmorfs dentries are always dropped from the dentry cache
when the usage count drops to zero, there is no guarantee that this will
happen in aafs_remove(), as another thread might still be using it. In
this scenario, this means that the dentry will temporarily continue to
appear in the results of lookups, even after the call to aafs_remove().

In the case of removal of a profile - it also causes simple_rmdir()
on the profile directory to fail, as the directory won't be empty until
the usage counts of all child dentries have decreased to zero. This
results in the dentry for the profile directory leaking and appearing
empty in the file system tree forever.

Signed-off-by: Chris Coulson <chris.coulson@...onical.com>
Signed-off-by: John Johansen <john.johansen@...onical.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 security/apparmor/apparmorfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index dd746bd69a9b2..c106988c1b254 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -363,6 +363,7 @@ static void aafs_remove(struct dentry *dentry)
 			simple_rmdir(dir, dentry);
 		else
 			simple_unlink(dir, dentry);
+		d_delete(dentry);
 		dput(dentry);
 	}
 	inode_unlock(dir);
-- 
2.20.1