xfs: validate acl count

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 <bpm@sgi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/xfs/linux-2.6/xfs_acl.c b/fs/xfs/linux-2.6/xfs_acl.c
index 4c7b14503716d3e01bfee8d48ab930f6fdbd008a..03aec610b3fcaf3dce00aceb3982b30fa30a8847 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_acl.c
+++ b/fs/xfs/linux-2.6/xfs_acl.c
@@ -40,6 +40,8 @@ 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)