Re: [PATCH 167/241] SUNRPC: Set alloc_slot for backchannel tcp ops

[Ben Hutchings]

On Thu, 2012-12-13 at 11:58 -0200, Herton Ronaldo Krzesinski wrote:
> 3.5.7.2 -stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Bryan Schumaker <bjschuma@xxxxxxxxxx>
> 
> commit 84e28a307e376f271505af65a7b7e212dd6f61f4 upstream.
> 
> f39c1bfb5a03e2d255451bff05be0d7255298fa4 (SUNRPC: Fix a UDP transport
> regression) introduced the "alloc_slot" function for xprt operations,
> but never created one for the backchannel operations.  This patch fixes
> a null pointer dereference when mounting NFS over v4.1.
[...]

Greg, you missed this in 3.4.y.  It might need a context fix; I'm
attaching the version I used for 3.2.y.

Ben.

-- 
Ben Hutchings
Theory and practice are closer in theory than in practice.
                                - John Levine, moderator of comp.compilers
From: Bryan Schumaker <bjschuma@xxxxxxxxxx>
Date: Mon, 24 Sep 2012 13:39:01 -0400
Subject: SUNRPC: Set alloc_slot for backchannel tcp ops

commit 84e28a307e376f271505af65a7b7e212dd6f61f4 upstream.

f39c1bfb5a03e2d255451bff05be0d7255298fa4 (SUNRPC: Fix a UDP transport
regression) introduced the "alloc_slot" function for xprt operations,
but never created one for the backchannel operations.  This patch fixes
a null pointer dereference when mounting NFS over v4.1.

Call Trace:
 [<ffffffffa0207957>] ? xprt_reserve+0x47/0x50 [sunrpc]
 [<ffffffffa02023a4>] call_reserve+0x34/0x60 [sunrpc]
 [<ffffffffa020e280>] __rpc_execute+0x90/0x400 [sunrpc]
 [<ffffffffa020e61a>] rpc_async_schedule+0x2a/0x40 [sunrpc]
 [<ffffffff81073589>] process_one_work+0x139/0x500
 [<ffffffff81070e70>] ? alloc_worker+0x70/0x70
 [<ffffffffa020e5f0>] ? __rpc_execute+0x400/0x400 [sunrpc]
 [<ffffffff81073d1e>] worker_thread+0x15e/0x460
 [<ffffffff8145c839>] ? preempt_schedule+0x49/0x70
 [<ffffffff81073bc0>] ? rescuer_thread+0x230/0x230
 [<ffffffff81079603>] kthread+0x93/0xa0
 [<ffffffff81465d04>] kernel_thread_helper+0x4/0x10
 [<ffffffff81079570>] ? kthread_freezable_should_stop+0x70/0x70
 [<ffffffff81465d00>] ? gs_change+0x13/0x13

Signed-off-by: Bryan Schumaker <bjschuma@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/sunrpc/xprtsock.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -2488,6 +2488,7 @@ static struct rpc_xprt_ops xs_tcp_ops =
 static struct rpc_xprt_ops bc_tcp_ops = {
 	.reserve_xprt		= xprt_reserve_xprt,
 	.release_xprt		= xprt_release_xprt,
+	.alloc_slot		= xprt_alloc_slot,
 	.buf_alloc		= bc_malloc,
 	.buf_free		= bc_free,
 	.send_request		= bc_send_request,

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