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authorChristoph Hellwig <hch@lst.de>2014-05-04 13:03:32 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-07 13:25:33 -0700
commit3d3da408c35c3d674e29d56b19db2e37058bf2dc (patch)
treeb9bd6243080ebe842f371f6d5307627450ffa2d3
parent0d38fa9f117581424fc06825aa8d32ad48548d25 (diff)
downloadlinux-linaro-stable-3d3da408c35c3d674e29d56b19db2e37058bf2dc.tar.gz
posix_acl: handle NULL ACL in posix_acl_equiv_mode
commit 50c6e282bdf5e8dabf8d7cf7b162545a55645fd9 upstream. 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 <hch@lst.de> Reported-by: Ben Greear <greearb@candelatech.com> Reported-by: Marco Munderloh <munderl@tnt.uni-hannover.de>, Cc: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/posix_acl.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 8bd2135b7f82..3542f1f814e2 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -158,6 +158,12 @@ 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: