On Mon, Sep 24, 2012 at 07:31:23PM +0000, Myklebust, Trond wrote:
> On Mon, 2012-09-24 at 13:52 -0400, Bryan Schumaker wrote:
> > On 09/24/2012 01:42 PM, J. Bruce Fields wrote:
> > > On Mon, Sep 24, 2012 at 01:39:01PM -0400, bjschuma@xxxxxxxxxx wrote:
> > >> From: Bryan Schumaker <bjschuma@xxxxxxxxxx>
> > >>
> > >> 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.
> > >
> > > Thanks, I just rebased some of my work to 3.6 and ran across that! It
> > > crashes the 4.1 server very quickly....
> >
> > That sounds like my story. It got my peer-to-peer server right away, too.
> >
> > - Bryan
> >
> > >
> > > --b.
> > >
> > >>
> > >> 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>
> > >> ---
> > >> net/sunrpc/xprtsock.c | 1 +
> > >> 1 file changed, 1 insertion(+)
> > >>
> > >> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> > >> index 86b7777..aaaadfb 100644
> > >> --- a/net/sunrpc/xprtsock.c
> > >> +++ b/net/sunrpc/xprtsock.c
> > >> @@ -2521,6 +2521,7 @@ 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,
> > >> .rpcbind = xs_local_rpcbind,
> > >> .buf_alloc = bc_malloc,
> > >> .buf_free = bc_free,
> > >> --
> > >> 1.7.12.1
> > >>
> > >> --
> > >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> > >> the body of a message to majordomo@xxxxxxxxxxxxxxx
> > >> More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
>
> Argh... Sorry, that was entirely my fault. I traced the client side
> backchannel code, and found it was allocating slots using its own
> mechanism, then thought that applied to bc_tcp_ops.
>
> I find the NFSv4.1 backchannel code to be even more confusing than
> lockd.
Patches very much welcomed.
> ...and BTW the .rpcbind hack above is a prime example. Bruce, why do you
> need that? The server back channel sets xprt_set_bound() in
> xs_setup_bc_tcp() and should never clear it.
Beats me; you're suggesting the below? Agreed, looks wrong.
It must be pointless in the AF_LOCAL case too, though I didn't try to
verify.
--b.
commit ad25de5558f702fa2c7ececedf4d61975dababa8
Author: J. Bruce Fields <bfields@xxxxxxxxxx>
Date: Mon Sep 24 15:53:29 2012 -0400
sunrpc: server back channel needs no rpcbind method
XPRT_BOUND is set on server backchannel xprts by xs_setup_bc_tcp()
(using xprt_set_bound()), and is never cleared, so ->rpcbind() will
never need to be called.
Reported-by: "Myklebust, Trond" <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index cd59a80..3a8663e6 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -2529,7 +2529,6 @@ static struct rpc_xprt_ops bc_tcp_ops = {
.reserve_xprt = xprt_reserve_xprt,
.release_xprt = xprt_release_xprt,
.alloc_slot = xprt_alloc_slot,
- .rpcbind = xs_local_rpcbind,
.buf_alloc = bc_malloc,
.buf_free = bc_free,
.send_request = bc_send_request,
--
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