[ 042/171] SUNRPC: Fix validity issues with rpc_pipefs sb->s_fs_info

Greg Kroah-Hartman
2013-01-15T23:52:32Z

From: Trond Myklebust <Trond.Myklebust@netapp.com>

commit 642fe4d00db56d65060ce2fd4c105884414acb16 upstream.

rpc_kill_sb() must defer calling put_net() until after the notifier
has been called, since most (all?) of the notifier callbacks assume
that sb->s_fs_info points to a valid net namespace. It also must not
call put_net() if the call to rpc_fill_super was unsuccessful.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=48421

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/sunrpc/rpc_pipe.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1157,14 +1157,19 @@ static void rpc_kill_sb(struct super_blo
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

mutex_lock(&sn->pipefs_sb_lock);
+ if (sn->pipefs_sb != sb) {
+ mutex_unlock(&sn->pipefs_sb_lock);
+ goto out;
+ }
sn->pipefs_sb = NULL;
mutex_unlock(&sn->pipefs_sb_lock);
- put_net(net);
dprintk("RPC: sending pipefs UMOUNT notification for net %p%s\n", net,
NET_NAME(net));
blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
RPC_PIPEFS_UMOUNT,
sb);
+ put_net(net);
+out:
kill_litter_super(sb);
}