From: NeilBrown Date: Thu, 13 Dec 2012 04:14:36 +0000 (+1100) Subject: NFS: avoid NULL dereference in nfs_destroy_server X-Git-Tag: firefly_0821_release~7541^2~199 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=64b45c804286cb18c50b387169b7da64279bc1ed;p=firefly-linux-kernel-4.4.55.git NFS: avoid NULL dereference in nfs_destroy_server 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 Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/nfs/client.c b/fs/nfs/client.c index b3dc2b88b65b..0cb731f26fe9 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c @@ -673,8 +673,7 @@ static int nfs_create_rpc_client(struct nfs_client *clp, */ 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); }