[PATCHv4 2/3]posix_acl: Add the acl pointer check

[liu weni <qingshenlwy@gmail.com>]

Add two acl pointer checks before this function.

---

Signed-off-by: Liuwenyi <qingshenlwy@gmail.com>
CC: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 39df95a..0d2a7a2 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -150,6 +150,12 @@ posix_acl_equiv_mode(const struct posix_acl *acl,
mode_t *mode_p)
 	mode_t mode = 0;
 	int not_equiv = 0;

+	if (!acl)
+		return -EINVAL;
+
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+
 	FOREACH_ACL_ENTRY(pa, acl, pe) {
 		switch (pa->e_tag) {
 			case ACL_USER_OBJ: