From patchwork Mon Apr 29 18:00:31 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthieu Baerts (NGI0)" X-Patchwork-Id: 13647492 X-Patchwork-Delegate: matthieu.baerts@tessares.net Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0855883CBA; Mon, 29 Apr 2024 18:01:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714413693; cv=none; b=IPKxnvrKSmfUUydyeuvv+3gHk+mEEkaMKfjukZkWp92dSM7aKXKWxsU9A78biZAbQ0vZWtHEB8LzzwGNyUmIWf28IxJy9XmTSqWRTXmyWS4uK6sI8KL5kHnJyFq+YUJ8XcBVcvkqVi6Sc7n1BYTE0TRqIpOfQF+PQSft4Sut2EA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714413693; c=relaxed/simple; bh=HnQX04g3H4aGl0kOgsahnA7O/urfcjX5rQYi9xXRvfA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=S9cmJV5kgG6H3ZebeA1uk4NxMll5VD4InFNDjnr2djfbLOFZQm+4banu/B+ftsRhmrZmCDbRA1kVF80DyiJg80uLhX3Vgb2RO7AarE5vzg2MZnS9Tm9Dw8am+B9EeNL68SD/x/sQo1/Ls8+tG/UNcyQ9oPpg3CY1F7jZwLajlnU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=l4r0V0Cj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="l4r0V0Cj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAD37C113CD; Mon, 29 Apr 2024 18:01:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714413692; bh=HnQX04g3H4aGl0kOgsahnA7O/urfcjX5rQYi9xXRvfA=; h=From:Date:Subject:To:Cc:From; b=l4r0V0Cj/ClfZtI2+M6SVJ009QE5l00rm0yGksF08mH8aqqq5eVFdU8auSlCHli5s KMaUrrs+eeXS+4DoYLqQuLDfQpSNcCQS7IrVlZvvwfj9w06E6REFcrHGWXFhu6TKW/ 54uecAJnjZYEJgDWhgYOHujTre977PDeYGFfTcqFtWVGZ6OPX4BS3GPygxr5Lol5SK cSAVULvtwjhttNae5v5OSkwJ8jJ1yJAOn/QFOgu2Gu6GualOlTzvTFhOXie83EGx38 4h9zIu5z+qFIs98WyeJjh2iqUpDWV2ZXACVsn7kxXpknVAqGudVdo0P/c8RmH4a5fc gRYJr1vvSYaWg== From: "Matthieu Baerts (NGI0)" Date: Mon, 29 Apr 2024 20:00:31 +0200 Subject: [PATCH net] mptcp: ensure snd_nxt is properly initialized on connect Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240429-upstream-net-20240429-mptcp-snd_nxt-init-connect-v1-1-59ceac0a7dcb@kernel.org> X-B4-Tracking: v=1; b=H4sIAD7gL2YC/z2NMQrDMAwAvxI0V+AaDU6/UkoJttJqiGIstQRC/ h7ToePdcLeDcRM2uA07NP6KyaodrpcB8nvSF6OUzhBDpEBxxE81bzwtqOz4t0v1XNG0PHVzFBX HvKpydixjIiophZkS9GxtPMv2W96hR+BxHCe/WyL+hwAAAA== To: mptcp@lists.linux.dev, Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Davide Caratti Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Christoph Paasch , "Matthieu Baerts (NGI0)" X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3765; i=matttbe@kernel.org; h=from:subject:message-id; bh=4DC3uSMFTJhiH+tjuyCzuGWfOrPmEvBhyUaXOn+ngXI=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBmL+B4xsRUyWBPNFj4ImKhOSMfiA0bEkPlKfCuo gS2+pFda4uJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZi/geAAKCRD2t4JPQmmg cw6ZEACKIZuD6B9nxlXS0mrv/rrVLtxTD70oRzZUAEY5D5RIIwQLC+cely9HUTKBrg/+OW1Uul/ hCidmg+XZGD0gghxawOeOhbLUo+n/xzrHtgU+AgYsS1+jHUG5zHaj9T2NhBpGWQLEPxYzB3LbIF iDDDkqwPB8CfD/Va08UQsu13wsGxCepM7Rc2devVjvCIBpKvUqlwKNXNa5nAmMGl2jk0d4mP7S9 h+7RrYVDRZd65Dh3eAKsyR/fwS7DTsiaZRu8yJ6hsFlMk3xTpxLqjHvvT7ptfCuLVaJllxNHlhZ WxxUF21HPSKrp3y5tEoUNIEswwsTyi76rwqk6HKBs96W1JVN1AtRg4Sk9NJgxa3eQ0DqU6TTvax ipbKBD4dGlccDNMlIAhotDmsnLT1tcijoSLZbP8uuQgUq1FwOK73uowh7oHo9foajmHfqSsCURr xaX2FSfdPcZ6SBRsyfkOracvUjTDAak+VwYEikjcy96KCEMhE/ry+r5oHzI48XjJSc0G1mRIQEI obG6HxfFElc7PIvHVkCzJ529aGzfkwrBzDTBRa4CWxKa32vhlBGGT2LqVwYkZDpDpxuP+5+qI1h l9DycXQaw2mgul0KadqjUw/xZa/3NGQecIWZkl5P7jn2ncyhtkx9zmsTsmjMj1ECxGbVj8KIEvc tSHTWSH50i7S89w== X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 From: Paolo Abeni 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: __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 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 Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/485 Tested-by: Christoph Paasch Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) --- net/mptcp/protocol.c | 3 +++ 1 file changed, 3 insertions(+) --- base-commit: ba1cb99b559e3b12db8b65ca9ff03358ea318064 change-id: 20240429-upstream-net-20240429-mptcp-snd_nxt-init-connect-d9844d880f48 Best regards, diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7e74b812e366..965eb69dc5de 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3723,6 +3723,9 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_TOKENFALLBACKINIT); mptcp_subflow_early_fallback(msk, subflow); } + + WRITE_ONCE(msk->write_seq, subflow->idsn); + WRITE_ONCE(msk->snd_nxt, subflow->idsn); if (likely(!__mptcp_check_fallback(msk))) MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVE);