* [PATCH 5.10.y] mptcp: ensure snd_nxt is properly initialized on connect [not found] <2024051325-dreamt-freebee-5563@gregkh> @ 2024-05-13 15:17 ` Matthieu Baerts (NGI0) 2024-05-23 12:03 ` Greg KH 0 siblings, 1 reply; 2+ messages in thread From: Matthieu Baerts (NGI0) @ 2024-05-13 15:17 UTC (permalink / raw) To: stable, gregkh Cc: MPTCP Upstream, Paolo Abeni, Christoph Paasch, Mat Martineau, Matthieu Baerts, Jakub Kicinski From: Paolo Abeni <pabeni@redhat.com> commit fb7a0d334894206ae35f023a82cad5a290fd7386 upstream. Christoph reported a splat hinting at a corrupted snd_una: WARNING: CPU: 1 PID: 38 at net/mptcp/protocol.c:1005 __mptcp_clean_una+0x4b3/0x620 net/mptcp/protocol.c:1005 Modules linked in: CPU: 1 PID: 38 Comm: kworker/1:1 Not tainted 6.9.0-rc1-gbbeac67456c9 #59 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 Workqueue: events mptcp_worker RIP: 0010:__mptcp_clean_una+0x4b3/0x620 net/mptcp/protocol.c:1005 Code: be 06 01 00 00 bf 06 01 00 00 e8 a8 12 e7 fe e9 00 fe ff ff e8 8e 1a e7 fe 0f b7 ab 3e 02 00 00 e9 d3 fd ff ff e8 7d 1a e7 fe <0f> 0b 4c 8b bb e0 05 00 00 e9 74 fc ff ff e8 6a 1a e7 fe 0f 0b e9 RSP: 0018:ffffc9000013fd48 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff8881029bd280 RCX: ffffffff82382fe4 RDX: ffff8881003cbd00 RSI: ffffffff823833c3 RDI: 0000000000000001 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: fefefefefefefeff R12: ffff888138ba8000 R13: 0000000000000106 R14: ffff8881029bd908 R15: ffff888126560000 FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f604a5dae38 CR3: 0000000101dac002 CR4: 0000000000170ef0 Call Trace: <TASK> __mptcp_clean_una_wakeup net/mptcp/protocol.c:1055 [inline] mptcp_clean_una_wakeup net/mptcp/protocol.c:1062 [inline] __mptcp_retrans+0x7f/0x7e0 net/mptcp/protocol.c:2615 mptcp_worker+0x434/0x740 net/mptcp/protocol.c:2767 process_one_work+0x1e0/0x560 kernel/workqueue.c:3254 process_scheduled_works kernel/workqueue.c:3335 [inline] worker_thread+0x3c7/0x640 kernel/workqueue.c:3416 kthread+0x121/0x170 kernel/kthread.c:388 ret_from_fork+0x44/0x50 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 </TASK> When fallback to TCP happens early on a client socket, snd_nxt is not yet initialized and any incoming ack will copy such value into snd_una. If the mptcp worker (dumbly) tries mptcp-level re-injection after such ack, that would unconditionally trigger a send buffer cleanup using 'bad' snd_una values. We could easily disable re-injection for fallback sockets, but such dumb behavior already helped catching a few subtle issues and a very low to zero impact in practice. Instead address the issue always initializing snd_nxt (and write_seq, for consistency) at connect time. Fixes: 8fd738049ac3 ("mptcp: fallback in case of simultaneous connect") Cc: stable@vger.kernel.org Reported-by: Christoph Paasch <cpaasch@apple.com> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/485 Tested-by: Christoph Paasch <cpaasch@apple.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://lore.kernel.org/r/20240429-upstream-net-20240429-mptcp-snd_nxt-init-connect-v1-1-59ceac0a7dcb@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> [ snd_nxt field is not available in v5.10.y: before, only write_seq was used, see commit eaa2ffabfc35 ("mptcp: introduce MPTCP snd_nxt") for more details about that. ] Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> --- net/mptcp/protocol.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 6be7e7592291..36fa456f42ba 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2645,6 +2645,8 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr, if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) mptcp_subflow_early_fallback(msk, subflow); + WRITE_ONCE(msk->write_seq, subflow->idsn); + do_connect: err = ssock->ops->connect(ssock, uaddr, addr_len, flags); sock->state = ssock->state; -- 2.43.0 ^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 5.10.y] mptcp: ensure snd_nxt is properly initialized on connect 2024-05-13 15:17 ` [PATCH 5.10.y] mptcp: ensure snd_nxt is properly initialized on connect Matthieu Baerts (NGI0) @ 2024-05-23 12:03 ` Greg KH 0 siblings, 0 replies; 2+ messages in thread From: Greg KH @ 2024-05-23 12:03 UTC (permalink / raw) To: Matthieu Baerts (NGI0) Cc: stable, MPTCP Upstream, Paolo Abeni, Christoph Paasch, Mat Martineau, Jakub Kicinski On Mon, May 13, 2024 at 05:17:17PM +0200, Matthieu Baerts (NGI0) wrote: > From: Paolo Abeni <pabeni@redhat.com> > > commit fb7a0d334894206ae35f023a82cad5a290fd7386 upstream. > > Christoph reported a splat hinting at a corrupted snd_una: > > WARNING: CPU: 1 PID: 38 at net/mptcp/protocol.c:1005 __mptcp_clean_una+0x4b3/0x620 net/mptcp/protocol.c:1005 > Modules linked in: > CPU: 1 PID: 38 Comm: kworker/1:1 Not tainted 6.9.0-rc1-gbbeac67456c9 #59 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 > Workqueue: events mptcp_worker > RIP: 0010:__mptcp_clean_una+0x4b3/0x620 net/mptcp/protocol.c:1005 > Code: be 06 01 00 00 bf 06 01 00 00 e8 a8 12 e7 fe e9 00 fe ff ff e8 > 8e 1a e7 fe 0f b7 ab 3e 02 00 00 e9 d3 fd ff ff e8 7d 1a e7 fe > <0f> 0b 4c 8b bb e0 05 00 00 e9 74 fc ff ff e8 6a 1a e7 fe 0f 0b e9 > RSP: 0018:ffffc9000013fd48 EFLAGS: 00010293 > RAX: 0000000000000000 RBX: ffff8881029bd280 RCX: ffffffff82382fe4 > RDX: ffff8881003cbd00 RSI: ffffffff823833c3 RDI: 0000000000000001 > RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 > R10: 0000000000000000 R11: fefefefefefefeff R12: ffff888138ba8000 > R13: 0000000000000106 R14: ffff8881029bd908 R15: ffff888126560000 > FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f604a5dae38 CR3: 0000000101dac002 CR4: 0000000000170ef0 > Call Trace: > <TASK> > __mptcp_clean_una_wakeup net/mptcp/protocol.c:1055 [inline] > mptcp_clean_una_wakeup net/mptcp/protocol.c:1062 [inline] > __mptcp_retrans+0x7f/0x7e0 net/mptcp/protocol.c:2615 > mptcp_worker+0x434/0x740 net/mptcp/protocol.c:2767 > process_one_work+0x1e0/0x560 kernel/workqueue.c:3254 > process_scheduled_works kernel/workqueue.c:3335 [inline] > worker_thread+0x3c7/0x640 kernel/workqueue.c:3416 > kthread+0x121/0x170 kernel/kthread.c:388 > ret_from_fork+0x44/0x50 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 > </TASK> > > When fallback to TCP happens early on a client socket, snd_nxt > is not yet initialized and any incoming ack will copy such value > into snd_una. If the mptcp worker (dumbly) tries mptcp-level > re-injection after such ack, that would unconditionally trigger a send > buffer cleanup using 'bad' snd_una values. > > We could easily disable re-injection for fallback sockets, but such > dumb behavior already helped catching a few subtle issues and a very > low to zero impact in practice. > > Instead address the issue always initializing snd_nxt (and write_seq, > for consistency) at connect time. > > Fixes: 8fd738049ac3 ("mptcp: fallback in case of simultaneous connect") > Cc: stable@vger.kernel.org > Reported-by: Christoph Paasch <cpaasch@apple.com> > Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/485 > Tested-by: Christoph Paasch <cpaasch@apple.com> > Signed-off-by: Paolo Abeni <pabeni@redhat.com> > Reviewed-by: Mat Martineau <martineau@kernel.org> > Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> > Link: https://lore.kernel.org/r/20240429-upstream-net-20240429-mptcp-snd_nxt-init-connect-v1-1-59ceac0a7dcb@kernel.org > Signed-off-by: Jakub Kicinski <kuba@kernel.org> > [ snd_nxt field is not available in v5.10.y: before, only write_seq was > used, see commit eaa2ffabfc35 ("mptcp: introduce MPTCP snd_nxt") for > more details about that. ] > Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> > --- > net/mptcp/protocol.c | 2 ++ > 1 file changed, 2 insertions(+) Now queued up, thanks. greg k-h ^ permalink raw reply [flat|nested] 2+ messages in thread
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2024-05-13 15:17 ` [PATCH 5.10.y] mptcp: ensure snd_nxt is properly initialized on connect Matthieu Baerts (NGI0)
2024-05-23 12:03 ` Greg KH
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