linux-kernel - [PATCH AUTOSEL 5.6 153/606] apparmor: Fix use-after-free in aa_audit_rule

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Message-Id: <20200608231211.3363633-153-sashal@kernel.org>
Date:   Mon,  8 Jun 2020 19:04:38 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Navid Emamdoost <navid.emamdoost@...il.com>,
        John Johansen <john.johansen@...onical.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-security-module@...r.kernel.org
Subject: [PATCH AUTOSEL 5.6 153/606] apparmor: Fix use-after-free in aa_audit_rule_init

From: Navid Emamdoost <navid.emamdoost@...il.com>

commit c54d481d71c6849e044690d3960aaebc730224cc upstream.

In the implementation of aa_audit_rule_init(), when aa_label_parse()
fails the allocated memory for rule is released using
aa_audit_rule_free(). But after this release, the return statement
tries to access the label field of the rule which results in
use-after-free. Before releasing the rule, copy errNo and return it
after release.

Fixes: 52e8c38001d8 ("apparmor: Fix memory leak of rule on error exit path")
Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.com>
Signed-off-by: John Johansen <john.johansen@...onical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 security/apparmor/audit.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/apparmor/audit.c b/security/apparmor/audit.c
index 5a98661a8b46..597732503815 100644
--- a/security/apparmor/audit.c
+++ b/security/apparmor/audit.c
@@ -197,8 +197,9 @@ int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
 	rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr,
 				     GFP_KERNEL, true, false);
 	if (IS_ERR(rule->label)) {
+		int err = PTR_ERR(rule->label);
 		aa_audit_rule_free(rule);
-		return PTR_ERR(rule->label);
+		return err;
 	}
 
 	*vrule = rule;
-- 
2.25.1