[PATCH 5.10 01/74] selinux: fix double free of cond_list on error paths

Greg Kroah-Hartman
2022-02-07T11:44:59Z

From: Vratislav Bendel <vbendel@redhat.com>

commit 186edf7e368c40d06cf727a1ad14698ea67b74ad upstream.

On error path from cond_read_list() and duplicate_policydb_cond_list()
the cond_list_destroy() gets called a second time in caller functions,
resulting in NULL pointer deref. Fix this by resetting the
cond_list_len to 0 in cond_list_destroy(), making subsequent calls a
noop.

Also consistently reset the cond_list pointer to NULL after freeing.

Cc: stable@vger.kernel.org
Signed-off-by: Vratislav Bendel <vbendel@redhat.com>
[PM: fix line lengths in the description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/selinux/ss/conditional.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/security/selinux/ss/conditional.c
+++ b/security/selinux/ss/conditional.c
@@ -152,6 +152,8 @@ static void cond_list_destroy(struct pol
for (i = 0; i < p->cond_list_len; i++)
cond_node_destroy(&p->cond_list[i]);
kfree(p->cond_list);
+ p->cond_list = NULL;
+ p->cond_list_len = 0;
}

void cond_policydb_destroy(struct policydb *p)
@@ -440,7 +442,6 @@ int cond_read_list(struct policydb *p, v
return 0;
err:
cond_list_destroy(p);
- p->cond_list = NULL;
return rc;
}