| Date | Fri, 28 Dec 2012 20:05:38 +0100 | From | Ben Hutchings <> | Subject | [ 128/173] NFS: avoid NULL dereference in nfs_destroy_server |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown <neilb@suse.de>
commit f259613a1e4b44a0cf85a5dafd931be96ee7c9e5 upstream.
In rare circumstances, nfs_clone_server() of a v2 or v3 server can get an error between setting server->destory (to nfs_destroy_server), and calling nfs_start_lockd (which will set server->nlm_host).
If this happens, nfs_clone_server will call nfs_free_server which will call nfs_destroy_server and thence nlmclnt_done(NULL). This causes the NULL to be dereferenced.
So add a guard to only call nlmclnt_done() if ->nlm_host is not NULL.
The other guards there are irrelevant as nlm_host can only be non-NULL if one of these flags are set - so remove those tests. (Thanks to Trond for this suggestion).
This is suitable for any stable kernel since 2.6.25.
Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- fs/nfs/client.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/nfs/client.c b/fs/nfs/client.c index c285e0a..9f3c664 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c @@ -615,8 +615,7 @@ EXPORT_SYMBOL_GPL(nfs_create_rpc_client); */ static void nfs_destroy_server(struct nfs_server *server) { - if (!(server->flags & NFS_MOUNT_LOCAL_FLOCK) || - !(server->flags & NFS_MOUNT_LOCAL_FCNTL)) + if (server->nlm_host) nlmclnt_done(server->nlm_host); }
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