From 11c3627ec6b56c1525013f336f41b79a983b4d46 Mon Sep 17 00:00:00 2001
From: Xin Xiong <xiongx18@fudan.edu.cn>
Date: Thu, 28 Apr 2022 11:39:08 +0800
Subject: [PATCH] apparmor: fix reference count leak in aa_pivotroot()
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Git-commit: 11c3627ec6b56c1525013f336f41b79a983b4d46
Patch-mainline: v6.0-rc1
References: git-fixes

The aa_pivotroot() function has a reference counting bug in a specific
path. When aa_replace_current_label() returns on success, the function
forgets to decrement the reference count of “target”, which is
increased earlier by build_pivotroot(), causing a reference leak.

Fix it by decreasing the refcount of “target” in that path.

Fixes: 2ea3ffb7782a ("apparmor: add mount mediation")
Co-developed-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Co-developed-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 security/apparmor/mount.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/security/apparmor/mount.c b/security/apparmor/mount.c
index 5cc5de062fc8..fa64a2db3aec 100644
--- a/security/apparmor/mount.c
+++ b/security/apparmor/mount.c
@@ -719,6 +719,7 @@ int aa_pivotroot(struct aa_label *label, const struct path *old_path,
 			aa_put_label(target);
 			goto out;
 		}
+		aa_put_label(target);
 	} else
 		/* already audited error */
 		error = PTR_ERR(target);
-- 
2.35.3