From aa449a7965a6172a89d48844c313708962216f1f Mon Sep 17 00:00:00 2001 From: Tom Rix Date: Mon, 15 Jun 2020 13:45:48 -0700 Subject: [PATCH] selinux: fix a double free in cond_read_node()/cond_read_list() 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. Cc: stable@vger.kernel.org Fixes: 60abd3181db2 ("selinux: convert cond_list to array") Signed-off-by: Tom Rix Reviewed-by: Ondrej Mosnacek [PM: subject line tweaks] Signed-off-by: Paul Moore --- security/selinux/ss/conditional.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c index 939a74fd8fb4..4867dfc5337a 100644 --- a/security/selinux/ss/conditional.c +++ b/security/selinux/ss/conditional.c @@ -392,27 +392,19 @@ 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; - } + if (!expr_node_isvalid(p, expr)) + return -EINVAL; } rc = cond_read_av_list(p, fp, &node->true_list, NULL); if (rc) - goto err; - 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; + return rc; + return cond_read_av_list(p, fp, &node->false_list, &node->true_list); } int cond_read_list(struct policydb *p, void *fp)