NFSv4.x: hide array-bounds warning

commit d55b352b01bc78fbc3d1bb650140668b87e58bf9 upstream.

A correct bugfix introduced a harmless warning that shows up with gcc-7:

fs/nfs/callback.c: In function 'nfs_callback_up':
fs/nfs/callback.c:214:14: error: array subscript is outside array bounds [-Werror=array-bounds]

What happens here is that the 'minorversion == 0' check tells the
compiler that we assume minorversion can be something other than 0,
but when CONFIG_NFS_V4_1 is disabled that would be invalid and
result in an out-of-bounds access.

The added check for IS_ENABLED(CONFIG_NFS_V4_1) tells gcc that this
really can't happen, which makes the code slightly smaller and also
avoids the warning.

The bugfix that introduced the warning is marked for stable backports,
we want this one backported to the same releases.

Fixes: 98b0f80c2396 ("NFSv4.x: Fix a refcount leak in nfs_callback_up_net")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 52a28311e2a4b2d72063cf36ac9e4296481211b7..48efe62e1302cc106cd661d8b62d199f347807c5 100644 (file)
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -261,7 +261,7 @@ static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
        }
 
        ret = -EPROTONOSUPPORT;
-       if (minorversion == 0)
+       if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
                ret = nfs4_callback_up_net(serv, net);
        else if (xprt->ops->bc_up)
                ret = xprt->ops->bc_up(serv, net);