4.14-stable review patch. If anyone has any objections, please let me know.
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From: "Bill.Baker@oracle.com" Bill.Baker@oracle.com
[ Upstream commit ad86f605c59500da82d196ac312cfbac3daba31d ]
nfs4_update_server unconditionally releases the nfs_client for the source server. If migration fails, this can cause the source server's nfs_client struct to be left with a low reference count, resulting in use-after-free. Also, adjust reference count handling for ELOOP.
NFS: state manager: migration failed on NFSv4 server nfsvmu10 with error 6 WARNING: CPU: 16 PID: 17960 at fs/nfs/client.c:281 nfs_put_client+0xfa/0x110 [nfs]() nfs_put_client+0xfa/0x110 [nfs] nfs4_run_state_manager+0x30/0x40 [nfsv4] kthread+0xd8/0xf0
BUG: unable to handle kernel NULL pointer dereference at 00000000000002a8 nfs4_xdr_enc_write+0x6b/0x160 [nfsv4] rpcauth_wrap_req+0xac/0xf0 [sunrpc] call_transmit+0x18c/0x2c0 [sunrpc] __rpc_execute+0xa6/0x490 [sunrpc] rpc_async_schedule+0x15/0x20 [sunrpc] process_one_work+0x160/0x470 worker_thread+0x112/0x540 ? rescuer_thread+0x3f0/0x3f0 kthread+0xd8/0xf0
This bug was introduced by 32e62b7c ("NFS: Add nfs4_update_server"), but the fix applies cleanly to 52442f9b ("NFS4: Avoid migration loops")
Reported-by: Helen Chao helen.chao@oracle.com Fixes: 52442f9b11b7 ("NFS4: Avoid migration loops") Signed-off-by: Bill Baker bill.baker@oracle.com Reviewed-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Trond Myklebust trond.myklebust@primarydata.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nfs/nfs4client.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/nfs/nfs4client.c +++ b/fs/nfs/nfs4client.c @@ -858,8 +858,10 @@ static int nfs4_set_client(struct nfs_se if (IS_ERR(clp)) return PTR_ERR(clp);
- if (server->nfs_client == clp) + if (server->nfs_client == clp) { + nfs_put_client(clp); return -ELOOP; + }
/* * Query for the lease time on clientid setup or renewal @@ -1217,11 +1219,11 @@ int nfs4_update_server(struct nfs_server clp->cl_proto, clnt->cl_timeout, clp->cl_minorversion, net); clear_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status); - nfs_put_client(clp); if (error != 0) { nfs_server_insert_lists(server); return error; } + nfs_put_client(clp);
if (server->nfs_client->cl_hostname == NULL) server->nfs_client->cl_hostname = kstrdup(hostname, GFP_KERNEL);