[41/42] xfs: validate acl count

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

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

From: Christoph Hellwig <hch@infradead.org>

commit fa8b18edd752a8b4e9d1ee2cd615b82c93cf8bba upstream.

This prevents in-memory corruption and possible panics if the on-disk
ACL is badly corrupted.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 fs/xfs/xfs_acl.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c

@@ -42,6 +42,8 @@ xfs_acl_from_disk(struct xfs_acl *aclp)
 	int count, i;
 
 	count = be32_to_cpu(aclp->acl_cnt);
+	if (count > XFS_ACL_MAX_ENTRIES)
+		return ERR_PTR(-EFSCORRUPTED);
 
 	acl = posix_acl_alloc(count, GFP_KERNEL);
 	if (!acl)