From: Cedric Le Goater Subject: [PATCH] sunrpc: fix oops in rpc_create() when the mount namespace is unshared Date: Thu, 11 Sep 2008 11:14:10 +0200 Message-ID: <48C8E162.7050800@fr.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: linux-nfs@vger.kernel.org, Chuck Lever , Trond Myklebust , Andrew Morton , "Eric W. Biederman" , "Serge E. Hallyn" To: Linux Kernel Mailing List Return-path: Received: from mtagate5.uk.ibm.com ([195.212.29.138]:40831 "EHLO mtagate5.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751595AbYIKJQA (ORCPT ); Thu, 11 Sep 2008 05:16:00 -0400 Sender: linux-nfs-owner@vger.kernel.org List-ID: From: Cedric Le Goater On a system with nfs mounts, if a task unshares its mount namespace, a oops can occur when the system is rebooted if the task is the last to unreference the nfs mount. It will try to create a rpc request using utsname() which has been invalidated by free_nsproxy(). The patch fixes the issue by using the global init_utsname() which is always valid. the capability of identifying rpc clients per uts namespace stills needs some extra work so this should not be a problem. BUG: unable to handle kernel NULL pointer dereference at 00000004 IP: [] rpc_create+0x332/0x42f Oops: 0000 [#1] DEBUG_PAGEALLOC Pid: 1857, comm: uts-oops Not tainted (2.6.27-rc5-00319-g7686ad5 #4) EIP: 0060:[] EFLAGS: 00210287 CPU: 0 EIP is at rpc_create+0x332/0x42f EAX: 00000000 EBX: df26adf0 ECX: c0251887 EDX: 00000001 ESI: df26ae58 EDI: c02f293c EBP: dda0fc9c ESP: dda0fc2c DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 Process uts-oops (pid: 1857, ti=dda0e000 task=dd9a0778 task.ti=dda0e000) Stack: c0104532 dda0fffc dda0fcac dda0e000 dda0e000 dd93b7f0 00000009 c02f2880 df26aefc dda0fc68 c01096b7 00000000 c0266ee0 c039a070 c039a070 dda0fc74 c012ca67 c039a064 dda0fc8c c012cb20 c03daf74 00000011 00000000 c0275c90 Call Trace: [] ? dump_trace+0xc2/0xe2 [] ? save_stack_trace+0x1c/0x3a [] ? save_trace+0x37/0x8c [] ? add_lock_to_list+0x64/0x96 [] ? rpcb_register_call+0x62/0xbb [] ? rpcb_register+0xab/0xb3 [] ? svc_register+0xb4/0x128 [] ? svc_destroy+0xec/0x103 [] ? svc_exit_thread+0x87/0x8d [] ? lockd_down+0x61/0x81 [] ? nlmclnt_done+0xd/0xf [] ? nfs_destroy_server+0x14/0x16 [] ? nfs_free_server+0x4c/0xaa [] ? nfs_kill_super+0x23/0x27 [] ? deactivate_super+0x3f/0x51 [] ? mntput_no_expire+0x95/0xb4 [] ? release_mounts+0x6b/0x7a [] ? __put_mnt_ns+0x62/0x70 [] ? free_nsproxy+0x25/0x80 [] ? switch_task_namespaces+0x3e/0x43 [] ? exit_task_namespaces+0xa/0xc [] ? do_exit+0x4fd/0x666 [] ? do_group_exit+0x5d/0x83 [] ? get_signal_to_deliver+0x2c8/0x2e0 [] ? do_notify_resume+0x69/0x700 [] ? do_sigaction+0x134/0x145 [] ? hrtimer_nanosleep+0x8f/0xce [] ? hrtimer_wakeup+0x0/0x1c [] ? work_notifysig+0x13/0x1b ======================= Code: 70 20 68 cb c1 2c c0 e8 75 4e 01 00 8b 83 ac 00 00 00 59 3d 00 f0 ff ff 5f 77 63 eb 57 a1 00 80 2d c0 8b 80 a8 02 00 00 8d 73 68 <8b> 40 04 83 c0 45 e8 41 46 f7 ff ba 20 00 00 00 83 f8 21 0f 4c EIP: [] rpc_create+0x332/0x42f SS:ESP 0068:dda0fc2c Signed-off-by: Cedric Le Goater --- net/sunrpc/clnt.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 76739e9..a59cdf4 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -213,10 +213,10 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru } /* save the nodename */ - clnt->cl_nodelen = strlen(utsname()->nodename); + clnt->cl_nodelen = strlen(init_utsname()->nodename); if (clnt->cl_nodelen > UNX_MAXNODENAME) clnt->cl_nodelen = UNX_MAXNODENAME; - memcpy(clnt->cl_nodename, utsname()->nodename, clnt->cl_nodelen); + memcpy(clnt->cl_nodename, init_utsname()->nodename, clnt->cl_nodelen); rpc_register_client(clnt); return clnt; -- 1.5.5.1