From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj2-f40.google.com (mail-pj2-f40.google.com [74.125.227.168]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 92D6C3EEAF9 for ; Sun, 27 Sep 2026 13:10:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.168 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790514630; cv=none; b=HiSf2oq7VEybUcrM3ZHkFAUOJfOZoOI7NgHqEKTF48TLO9ooavaeRAJqNoWnAdjwQ8U2k2wsGqf/EyOigrW6PDLp96QvsG9QNMBxhwy8wo/OdJg3240KojxefbBjic+J8lulMMhbh17Mq5C4lwTLdeyH5HEsPE49sttIQP76348= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790514630; c=relaxed/simple; bh=HBEZ8gvSuuTPFRjoDeYmiebMx2iMq5KUi9vEstX2HoI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=CYEqYwonc/uLPMNopOEyYLt0oAKnZQBtd3XJLzD4SaUrqXMMNtTxR5MPfH1874q7NlBqlGTJyNJAn80Ji4DwzaERhwYU2t1TTrCgrI0yEwdi3KlzjC1ZC3dTLrv+XD65Hho49iXA1+2/Xw5NI86d1kXEuW+UinnCOtYcgncv1kI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Ktd/Ke2u; arc=none smtp.client-ip=74.125.227.168 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Ktd/Ke2u" Received: by mail-pj2-f40.google.com with SMTP id 98e67ed59e1d1-3a0d31bda43so957358a91.1 for ; Sun, 27 Sep 2026 06:10:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790514629; x=1791119429; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=bkDmzZIfjmIBLLdMK74q6txJ55ZXC/oT66ennoBB6nM=; b=Ktd/Ke2ulLTbNok0HLAA7F3DBiha7pSO5tXXOAW6iMLuHYuKRH6BT93iJnlgZMEdUa b4rIOmhNg3rU8um8FVopGudbry66y1iftvcNVHX96vSI3Ue3z3kkAQuBRz+uEB0WDt5P u3XmALWq1EPmZyzjvSsl1oSchdrORzwzJjjCv6lmNOeUriKtPkxduN7dHcN0X7q/CuUh HmJ0C2B+bHdnWx1yF6E3mOjXHSKEQJs78ppNz5u8i8vjhmFnr6+4eRrRNRfriXgLIGvB DEfGUVx1V39Ib/Wb1xSBoEOwWv24Wbfy0UEBGXbJixB2sTC4h4l+rOWxbQC54QmA/Jtj NcVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790514629; x=1791119429; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=bkDmzZIfjmIBLLdMK74q6txJ55ZXC/oT66ennoBB6nM=; b=jCz2//BgyfnhqI+hp+5R/+L2ew5HajMGzvFAdyAglvTvlCxpa03wUEhi1fgOm93KbE vdReBotp0mUNzkcP8P7RxjwlcMJNTvU/jmP3tHlcGNs3ori3m86a8DF+nx39uRXrqkhL yuaQoZkIjfr/wO8xYCVnBHt9m/I+ZM/GWmzaUhAiK5NK2clkyTYvAsFd05rrb3xR2VWw h3G3e/veOOMpgQH5UO10eYGmWaFVs0gu4ML95+vXigwwfuaww1t0uxOM2hBd7lZHrQk7 ZPQqJ/oGGWzFWEpjFjPRgUMjnFX0dMz9w9KqkRRv/o6CICA7nllN5+Pu6/tjdpyz7GI7 OKiQ== X-Forwarded-Encrypted: i=1; AKwUvBxUOFGnLRPBGk2m1s6sXyyXMTnfsLXZyKQxBQB+/xwaam+Wo8wTD80mAB71ehIfTBveI/HIiB8=@vger.kernel.org X-Gm-Message-State: AFq9FYKl8jBqPP/SAJ8F06dFYcAu4J5zhBk9uQUkxYbepMnpQEae6tJD nRzUStTqPhW+W15Mm2i72DBvI/i360TslRuU6S7jhTlxAUDUQsLcAzo6 X-Gm-Gg: AYBFou34hIUBixip596JAzhfcYFKQ+tCBxhVR6CDEq9xU/mVaddhVhMg6OrcisBFecd Sgl6KlQwvDM7Z0oXGC6xtx5MFIlYg3gZqYmy4Jh1o5U0qfzukMAiYQefNLCO/yqS9dQYydUf5hs DnlsQs5dGSLUGaseLDqpRZOngadpOQU75j9xQOMAgGXV1suXojuu11yn5+uN8FaAbb41kgIn3MF wfdkdAEdaMMgZQa81puNpU27OCDV9jYt6c4PlWUZ/WHrhv1hDOCUuPA4xE30qXSsEWQLstde/tb CIy/xXv2xDY6Cb1B2GW579vLytJkE59zihJ3TKQAi/NcEHRPRE7kSs1yQuecQIi8NyVaiknz02r QJm6d/0BcPKfwVLiOxZ7OadHNAfEVz3KRthOY4HaEBufb/Tewpyc7EDbQrHxoVCDNtmD8L6Pg8S 1ui+7zKbt7WlrAq00E7v6H4RVeFlpBV98h3bWSoh0sDNQUNYaga84zdUUBHbK7zASTqMzWbL5Ic NZzbDt6dqSzgD/nDy3u90sNmThpJzxKDTk= X-Received: by 2002:a17:90a:d883:b0:3a0:2900:f577 with SMTP id 98e67ed59e1d1-3a098dff5b4mr8264184a91.51.1790514628797; Sun, 27 Sep 2026 06:10:28 -0700 (PDT) Received: from localhost.localdomain ([2409:8a1e:2e81:7320:84a7:e3d7:8c7e:980a]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a0b9589f7esm14890506a91.10.2026.09.27.06.10.20 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 27 Sep 2026 06:10:27 -0700 (PDT) From: Yuchao Zhang To: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Jamal Hadi Salim , Jiri Pirko , cake@lists.bufferbloat.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Yuchao Zhang Subject: [PATCH net v3 0/2] net/sched: sch_cake: prevent shaper corruption and stall in cake_overhead() Date: Sun, 27 Sep 2026 21:10:07 +0800 Message-ID: <20260927131009.24250-1-ndaugoing@gmail.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This series addresses two issues in cake_overhead() that can lead to corrupted rate shaper accounting or long dequeue stalls: Patch 1 fixes an integer underflow when segs == 0. When an skb with segs == 0 (such as dodgy GSO packets where gso_segs is not recomputed) reaches cake_overhead(), (segs - 1) wraps around to UINT32_MAX, multiplying per-segment overhead by ~4.29 billion and returning a length close to 4.29 GB. cake_advance_shaper() then charges that length to the shaper, stalling the dequeue queue for tens of seconds at 1 Gbit/s, and for minutes to hours at lower rates. This was introduced by commit c5d34f4583ea ("net_sched: cake: use qdisc_pkt_segs()"). Patch 2 validates the transport header offset computed in cake_overhead(). When the transport header was never set, skb_transport_offset() returns the ~0U sentinel (~65535), which inflates shaper accounting by ~66 KB per segment. Furthermore, if preceding egress BPF filters (e.g. sch_handle_egress()) or cake classifier actions (e.g. act_bpf trimming headers via bpf_skb_adjust_room(BPF_ADJ_ROOM_MAC)) leave the transport header stale (bpf_skb_net_hdr_pop() only re-syncs it when it aliased network_header), skb_transport_offset() can become negative. Because hdr_len was declared as unsigned int, a negative offset wraps to near UINT_MAX. Patch 2 checks !skb_transport_header_was_set() and ensures hdr_len >= 0. Both hunks date back to commit a729b7f0bd5b ("sch_cake: Add overhead compensation support to the rate shaper"), so they share a single Fixes: tag and stable range. Changes in v3: - Split the v2 patch into a 2-patch series per Simon Horman and Sashiko AI review so each logical fix carries its own accurate Fixes: tag and matches proper stable tree backport ranges: - Patch 1 Fixes: c5d34f4583ea ("net_sched: cake: use qdisc_pkt_segs()") - Patch 2 Fixes: a729b7f0bd5b ("sch_cake: Add overhead compensation support to the rate shaper") - Clarify the timing and code paths where header mangling can occur (sch_handle_egress() and cake_classify() before cake_overhead()) rather than inaccurate "post-enqueue mangling" wording. - Link to v2: https://lore.kernel.org/netdev/20260922084124.36858-1-ndaugoing@gmail.com/ Changes in v2: - Accurately describe the impact as shaper accounting corruption / stall rather than OOB read past the allocation. - Fix integer underflow when segs == 0 by checking segs <= 1. - Import companion check !skb_transport_header_was_set(skb) from qdisc_pkt_len_segs_init() to prevent unset transport header sentinel (~0U) from inflating packet length to ~66 KB. - Link to v1: https://lore.kernel.org/netdev/20260917122153.62722-1-ndaugoing@gmail.com/ Yuchao Zhang (2): net/sched: sch_cake: fix shaper stall on segs == 0 in cake_overhead() net/sched: sch_cake: validate transport header offset in cake_overhead() net/sched/sch_cake.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) -- 2.53.0