nfsd4: reject "negative" acl lengths

commit 64a817cfbded8674f345d1117b117f942a351a69 upstream.

Since we only enforce an upper bound, not a lower bound, a "negative"
length can get through here.

The symptom seen was a warning when we attempt to a kmalloc with an
excessive size.

Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 0dc11586682fd7d93c85790af67bd8d83f6f9002..d1dd7100a556173743a423038c532dffa7811bb3 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -264,7 +264,7 @@ nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval,
                iattr->ia_valid |= ATTR_SIZE;
        }
        if (bmval[0] & FATTR4_WORD0_ACL) {
-               int nace;
+               u32 nace;
                struct nfs4_ace *ace;
 
                READ_BUF(4); len += 4;