[PATCH 4.9 001/103] 9p: fix a potential acl leak

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Cong Wang <xiyou.wangcong@xxxxxxxxx>

commit b5c66bab72a6a65edb15beb60b90d3cb84c5763b upstream.

posix_acl_update_mode() could possibly clear 'acl', if so we leak the
memory pointed by 'acl'.  Save this pointer before calling
posix_acl_update_mode() and release the memory if 'acl' really gets
cleared.

Link: http://lkml.kernel.org/r/1486678332-2430-1-git-send-email-xiyou.wangcong@xxxxxxxxx
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Reported-by: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Greg Kurz <groug@xxxxxxxx>
Cc: Eric Van Hensbergen <ericvh@xxxxxxxxx>
Cc: Ron Minnich <rminnich@xxxxxxxxxx>
Cc: Latchesar Ionkov <lucho@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/9p/acl.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -277,6 +277,7 @@ static int v9fs_xattr_set_acl(const stru
 	case ACL_TYPE_ACCESS:
 		if (acl) {
 			struct iattr iattr;
+			struct posix_acl *old_acl = acl;
 
 			retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
 			if (retval)
@@ -287,6 +288,7 @@ static int v9fs_xattr_set_acl(const stru
 				 * by the mode bits. So don't
 				 * update ACL.
 				 */
+				posix_acl_release(old_acl);
 				value = NULL;
 				size = 0;
 			}