From 50c6e282bdf5e8dabf8d7cf7b162545a55645fd9 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 4 May 2014 13:03:32 +0200 Subject: [PATCH] posix_acl: handle NULL ACL in posix_acl_equiv_mode Various filesystems don't bother checking for a NULL ACL in posix_acl_equiv_mode, and thus can dereference a NULL pointer when it gets passed one. This usually happens from the NFS server, as the ACL tools never pass a NULL ACL, but instead of one representing the mode bits. Instead of adding boilerplat to all filesystems put this check into one place, which will allow us to remove the check from other filesystems as well later on. Signed-off-by: Christoph Hellwig Reported-by: Ben Greear Reported-by: Marco Munderloh , Cc: Chuck Lever Cc: stable@vger.kernel.org Signed-off-by: Al Viro --- fs/posix_acl.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/posix_acl.c b/fs/posix_acl.c index 9e363e41dacc..0855f772cd41 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -246,6 +246,12 @@ posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) umode_t mode = 0; int not_equiv = 0; + /* + * A null ACL can always be presented as mode bits. + */ + if (!acl) + return 0; + FOREACH_ACL_ENTRY(pa, acl, pe) { switch (pa->e_tag) { case ACL_USER_OBJ: -- 2.30.2