Re: [PATCH 1/1] [SUNRPC] fix null pointer deref in tracepoints in back channel

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On Tue, 2019-03-12 at 12:06 -0400, Olga Kornievskaia wrote:
> From: Olga Kornievskaia <kolga@xxxxxxxxxx>
> 
> Backchannel doesn't have the rq_task->tk_clientid pointer set.
> 
> Otherwise can lead to the following oops:
> ocalhost login: [  111.385319] BUG: unable to handle kernel NULL
> pointer dereference at 0000000000000004
> [  111.388073] #PF error: [normal kernel read fault]
> [  111.389452] PGD 80000000290d8067 P4D 80000000290d8067 PUD 75f25067
> PMD 0
> [  111.391224] Oops: 0000 [#1] SMP PTI
> [  111.392151] CPU: 0 PID: 3533 Comm: NFSv4 callback Not tainted
> 5.0.0-rc7+ #1
> [  111.393787] Hardware name: VMware, Inc. VMware Virtual
> Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015
> [  111.396340] RIP:
> 0010:trace_event_raw_event_xprt_enq_xmit+0x6f/0xf0 [sunrpc]
> [  111.397974] Code: 00 00 00 48 89 ee 48 89 e7 e8 bd 0a 85 d7 48 85
> c0 74 4a 41 0f b7 94 24 e0 00 00 00 48 89 e7 89 50 08 49 8b 94 24 a8
> 00 00 00 <8b> 52 04 89 50 0c 49 8b 94 24 c0 00 00 00 8b 92 a8 00 00
> 00 0f ca
> [  111.402215] RSP: 0018:ffffb98743263cf8 EFLAGS: 00010286
> [  111.403406] RAX: ffffa0890fc3bc88 RBX: 0000000000000003 RCX:
> 0000000000000000
> [  111.405057] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> ffffb98743263cf8
> [  111.406656] RBP: ffffa0896f5368f0 R08: 0000000000000246 R09:
> 0000000000000000
> [  111.408437] R10: ffffe19b01c01500 R11: 0000000000000000 R12:
> ffffa08977d28a00
> [  111.410210] R13: 0000000000000004 R14: ffffa089315303f0 R15:
> ffffa08931530000
> [  111.411856] FS:  0000000000000000(0000) GS:ffffa0897bc00000(0000)
> knlGS:0000000000000000
> [  111.413699] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  111.415068] CR2: 0000000000000004 CR3: 000000002ac90004 CR4:
> 00000000001606f0
> [  111.416745] Call Trace:
> [  111.417339]  xprt_request_enqueue_transmit+0x2b6/0x4a0 [sunrpc]
> [  111.418709]  ? rpc_task_need_encode+0x40/0x40 [sunrpc]
> [  111.419957]  call_bc_transmit+0xd5/0x170 [sunrpc]
> [  111.421067]  __rpc_execute+0x7e/0x3f0 [sunrpc]
> [  111.422177]  rpc_run_bc_task+0x78/0xd0 [sunrpc]
> [  111.423212]  bc_svc_process+0x281/0x340 [sunrpc]
> [  111.424325]  nfs41_callback_svc+0x130/0x1c0 [nfsv4]
> [  111.425430]  ? remove_wait_queue+0x60/0x60
> [  111.426398]  kthread+0xf5/0x130
> [  111.427155]  ? nfs_callback_authenticate+0x50/0x50 [nfsv4]
> [  111.428388]  ? kthread_bind+0x10/0x10
> [  111.429270]  ret_from_fork+0x1f/0x30
> 
> localhost login: [  467.462259] BUG: unable to handle kernel NULL
> pointer dereference at 0000000000000004
> [  467.464411] #PF error: [normal kernel read fault]
> [  467.465445] PGD 80000000728c1067 P4D 80000000728c1067 PUD 728c0067
> PMD 0
> [  467.466980] Oops: 0000 [#1] SMP PTI
> [  467.467759] CPU: 0 PID: 3517 Comm: NFSv4 callback Not tainted
> 5.0.0-rc7+ #1
> [  467.469393] Hardware name: VMware, Inc. VMware Virtual
> Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015
> [  467.471840] RIP:
> 0010:trace_event_raw_event_xprt_transmit+0x7c/0xf0 [sunrpc]
> [  467.473392] Code: f6 48 85 c0 74 4b 49 8b 94 24 98 00 00 00 48 89
> e7 0f b7 92 e0 00 00 00 89 50 08 49 8b 94 24 98 00 00 00 48 8b 92 a8
> 00 00 00 <8b> 52 04 89 50 0c 41 8b 94 24 a8 00 00 00 0f ca 89 50 10
> 41 8b 94
> [  467.477605] RSP: 0018:ffffabe7434fbcd0 EFLAGS: 00010282
> [  467.478793] RAX: ffff99720fc3bce0 RBX: 0000000000000003 RCX:
> 0000000000000000
> [  467.480409] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> ffffabe7434fbcd0
> [  467.482011] RBP: ffff99726f631948 R08: 0000000000000246 R09:
> 0000000000000000
> [  467.483591] R10: 0000000070000000 R11: 0000000000000000 R12:
> ffff997277dfcc00
> [  467.485226] R13: 0000000000000000 R14: 0000000000000000 R15:
> ffff99722fecdca8
> [  467.486830] FS:  0000000000000000(0000) GS:ffff99727bc00000(0000)
> knlGS:0000000000000000
> [  467.488596] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  467.489931] CR2: 0000000000000004 CR3: 00000000270e6006 CR4:
> 00000000001606f0
> [  467.491559] Call Trace:
> [  467.492128]  xprt_transmit+0x303/0x3f0 [sunrpc]
> [  467.493143]  ? rpc_task_need_encode+0x40/0x40 [sunrpc]
> [  467.494328]  call_bc_transmit+0x49/0x170 [sunrpc]
> [  467.495379]  __rpc_execute+0x7e/0x3f0 [sunrpc]
> [  467.496451]  rpc_run_bc_task+0x78/0xd0 [sunrpc]
> [  467.497467]  bc_svc_process+0x281/0x340 [sunrpc]
> [  467.498507]  nfs41_callback_svc+0x130/0x1c0 [nfsv4]
> [  467.499751]  ? remove_wait_queue+0x60/0x60
> [  467.500686]  kthread+0xf5/0x130
> [  467.501438]  ? nfs_callback_authenticate+0x50/0x50 [nfsv4]
> [  467.502640]  ? kthread_bind+0x10/0x10
> [  467.503454]  ret_from_fork+0x1f/0x30
> 
> Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
> ---
>  include/trace/events/sunrpc.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/include/trace/events/sunrpc.h
> b/include/trace/events/sunrpc.h
> index 8451f30..7e899e6 100644
> --- a/include/trace/events/sunrpc.h
> +++ b/include/trace/events/sunrpc.h
> @@ -712,7 +712,8 @@
>  
>  	TP_fast_assign(
>  		__entry->task_id = rqst->rq_task->tk_pid;
> -		__entry->client_id = rqst->rq_task->tk_client->cl_clid;
> +		__entry->client_id = rqst->rq_task->tk_client ?
> +			rqst->rq_task->tk_client->cl_clid : -1;
>  		__entry->xid = be32_to_cpu(rqst->rq_xid);
>  		__entry->seqno = rqst->rq_seqno;
>  		__entry->status = status;
> @@ -742,7 +743,8 @@
>  
>  	TP_fast_assign(
>  		__entry->task_id = task->tk_pid;
> -		__entry->client_id = task->tk_client->cl_clid;
> +		__entry->client_id = task->tk_client ?
> +			task->tk_client->cl_clid : -1;
>  		__entry->xid = be32_to_cpu(task->tk_rqstp->rq_xid);
>  		__entry->seqno = task->tk_rqstp->rq_seqno;
>  		__entry->stage = stage;

Thanks Olga! Applied to linux-next...

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx






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