[PATCH 4.14 184/229] apparmor: fix reference count leak in aa_pivotroot()

Greg Kroah-Hartman
2022-08-23T10:13:20Z

From: Xin Xiong <xiongx18@fudan.edu.cn>

commit 11c3627ec6b56c1525013f336f41b79a983b4d46 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/apparmor/mount.c | 1 +
1 file changed, 1 insertion(+)

--- a/security/apparmor/mount.c
+++ b/security/apparmor/mount.c
@@ -687,6 +687,7 @@ int aa_pivotroot(struct aa_label *label,
aa_put_label(target);
goto out;
}
+ aa_put_label(target);
} else
/* already audited error */
error = PTR_ERR(target);