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>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index d86031b..c453a19 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned int layout_type)
                return NULL;
        }
 
-       if (!(exp->ex_layout_types & (1 << layout_type))) {
+       if (layout_type >= LAYOUT_TYPE_MAX ||
+           !(exp->ex_layout_types & (1 << layout_type))) {
                dprintk("%s: layout type %d not supported\n",
                        __func__, layout_type);
                return NULL;