From: trix@redhat.com
To: paul@paul-moore.com, stephen.smalley.work@gmail.com,
eparis@parisplace.org, omosnace@redhat.com,
weiyongjun1@huawei.com
Cc: selinux@vger.kernel.org, linux-kernel@vger.kernel.org,
Tom Rix <trix@redhat.com>
Subject: [PATCH v2 1/1] selinux: fix another double free
Date: Thu, 11 Jun 2020 13:47:46 -0700 [thread overview]
Message-ID: <20200611204746.6370-2-trix@redhat.com> (raw)
In-Reply-To: <20200611204746.6370-1-trix@redhat.com>
From: Tom Rix <trix@redhat.com>
Clang static analysis reports this double free error
security/selinux/ss/conditional.c:139:2: warning: Attempt to free released memory [unix.Malloc]
kfree(node->expr.nodes);
^~~~~~~~~~~~~~~~~~~~~~~
When cond_read_node fails, it calls cond_node_destroy which frees the
node but does not poison the entry in the node list. So when it
returns to its caller cond_read_list, cond_read_list deletes the
partial list. The latest entry in the list will be deleted twice.
So instead of freeing the node in cond_read_node, let list freeing in
code_read_list handle the freeing the problem node along with all of the
earlier nodes.
Because cond_read_node no longer does any error handling, the goto's
the error case are redundant. Instead just return the error code.
Fixes a problem was introduced by commit
selinux: convert cond_list to array
Signed-off-by: Tom Rix <trix@redhat.com>
---
security/selinux/ss/conditional.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c
index da94a1b4bfda..d0d6668709f0 100644
--- a/security/selinux/ss/conditional.c
+++ b/security/selinux/ss/conditional.c
@@ -392,26 +392,21 @@ static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
rc = next_entry(buf, fp, sizeof(u32) * 2);
if (rc)
- goto err;
+ return rc;
expr->expr_type = le32_to_cpu(buf[0]);
expr->bool = le32_to_cpu(buf[1]);
if (!expr_node_isvalid(p, expr)) {
rc = -EINVAL;
- goto err;
+ return rc;
}
}
rc = cond_read_av_list(p, fp, &node->true_list, NULL);
if (rc)
- goto err;
+ return rc;
rc = cond_read_av_list(p, fp, &node->false_list, &node->true_list);
- if (rc)
- goto err;
- return 0;
-err:
- cond_node_destroy(node);
return rc;
}
--
2.18.1
next prev parent reply other threads:[~2020-06-11 20:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 20:47 [PATCH v2 0/1] selinux: fix another double free trix
2020-06-11 20:47 ` trix [this message]
2020-06-11 22:30 ` [PATCH v2 1/1] " Paul Moore
2020-06-11 22:41 ` Tom Rix
2020-06-11 23:27 ` Paul Moore
2020-06-12 8:01 ` Ondrej Mosnacek
2020-06-12 13:30 ` Paul Moore
2020-06-12 7:51 ` Ondrej Mosnacek
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