linux-kernel - [PATCH 2/2] AppArmor: Fix lsm_get_self

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Date: Fri, 23 Feb 2024 20:05:46 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Casey Schaufler <casey@...aufler-ca.com>,
	John Johansen <john.johansen@...onical.com>,
	Paul Moore <paul@...l-moore.com>
Cc: Mickaël Salaün <mic@...ikod.net>,
	James Morris <jmorris@...ei.org>,
	"Serge E . Hallyn" <serge@...lyn.com>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH 2/2] AppArmor: Fix lsm_get_self_attr()

aa_getprocattr() may not initialize the value's pointer in some case.
As for proc_pid_attr_read(), initialize this pointer to NULL in
apparmor_getselfattr() to avoid an UAF in the kfree() call.

Cc: Casey Schaufler <casey@...aufler-ca.com>
Cc: John Johansen <john.johansen@...onical.com>
Cc: Paul Moore <paul@...l-moore.com>
Cc: stable@...r.kernel.org
Fixes: 223981db9baf ("AppArmor: Add selfattr hooks")
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
---
 security/apparmor/lsm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 98e1150bee9d..9a3dcaafb5b1 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -784,7 +784,7 @@ static int apparmor_getselfattr(unsigned int attr, struct lsm_ctx __user *lx,
 	int error = -ENOENT;
 	struct aa_task_ctx *ctx = task_ctx(current);
 	struct aa_label *label = NULL;
-	char *value;
+	char *value = NULL;
 
 	switch (attr) {
 	case LSM_ATTR_CURRENT:
-- 
2.43.0