nfsd: fix undefined behavior in nfsd4_layout_verify

  UBSAN: Undefined behaviour in fs/nfsd/nfs4proc.c:1262:34
  shift exponent 128 is too large for 32-bit type 'int'

Depending on compiler+architecture, this may cause the check for
layout_type to succeed for overly large values (which seems to be the
case with amd64). The large value will be later used in de-referencing
nfsd4_layout_ops for function pointers.

Reported-by: Jani Tuovila <tuovila@synopsys.com>
Signed-off-by: Ari Kauppi <ari@synopsys.com>
[colin.king@canonical.com: use LAYOUT_TYPE_MAX instead of 32]
Cc: stable@vger.kernel.org
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
(cherry picked from commit b550a32e60a4941994b437a8d662432a486235a5)

Orabug: 26376568
CVE: CVE-2017-8797

Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>
 Conflicts:
	fs/nfsd/nfs4proc.c

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 2b50bc0c545e0d50e9e206cfe8f036f065fc6063..75cca7e38ce2ab0c9cf2803466bfa75e4be94d03 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1194,7 +1194,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned int layout_type)
                return NULL;
        }
 
-       if (exp->ex_layout_type != layout_type) {
+       if (layout_type >= LAYOUT_TYPE_MAX || 
+           (exp->ex_layout_type != layout_type)) {
                dprintk("%s: layout type %d not supported\n",
                        __func__, layout_type);
                return NULL;