9p: fix a potential acl leak

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@gmail.com
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reported-by: Mark Salyzyn <salyzyn@android.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Greg Kurz <groug@kaod.org>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index b3c2cc79c20d255f5d3cdf59e407ad65c67c7089..082d227fa56b378772883f3a4254e7fd05c436d5 100644 (file)
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -277,6 +277,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
        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 struct xattr_handler *handler,
                                 * by the mode bits. So don't
                                 * update ACL.
                                 */
+                               posix_acl_release(old_acl);
                                value = NULL;
                                size = 0;
                        }