From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6565E4734D1 for ; Tue, 28 Jul 2026 19:30:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785267020; cv=none; b=t2syAOl0C/jRUJCmmgiRSr14hwE08HotJfs3vSlHv8xNiA7lkJnf76KWZ1poDKR3HZ99Cx0k/7j3Wmpz4vvqx4mqMNBAqZKpphR7ub8fdkdwVP49CV2E/g1ndaa0+hVFVALgWCX2pAw11L3RFJNIFF+G7Ejh9WwNjLD2rcqDCx0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785267020; c=relaxed/simple; bh=atp5mKZcKsncNUtpWiwXNHcC3usGLAAaFjxcYJKubfs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Dw5NKvndHpGWyHHoC5I4sp/9X1jOLLVySTpzrY9lqk0fBXw1+6Skek1JfLACPFJfVYIWe4TiT9dPgLJWnWzMbXLn7xSJgVgln9qRcoatA+J9w5O1s9gTadA8tsvADOODT2EVowzO8A/bZGVPlBR7422Tyc3TiB4kjk4JkBRS7gk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QvcFSv/n; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QvcFSv/n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 957641F00A3A; Tue, 28 Jul 2026 19:30:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785267019; bh=zjQ/M95/KYNv2ReDL4CU08Zlbb+/HlJrGdSlx7WxaFY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QvcFSv/nTTMCQIf6eTHoh8rO5bmLux05Mi7RljAvFibHhivd1dzGlvFmCSnyHU1fp nDW/yYPBB5qGCik8qblyH2qPz8uEZyP19TPGS3vB/HCN7BHgUFCrlmGC2Hx8oJlpb2 iv5vb179pmm3OgoKDHhsVHoVklNc6pu6CVlW2z930aMXbddw/ds8ZR+gkCONXvaymN 8dxWypSKlMCL4paF4rfhTtNdPxrjKuL8vy1L+ECwkTbNHTzNAxl21sSSb7gZm1PTyO bC5FNowVougMRhWlj2mNfpNJJPmKT+91yaF6Cp2ErpIF8/DNIo6KVLiccvoV9NCwpg O6dX3eEgv/zbg== From: Sasha Levin To: stable@vger.kernel.org Cc: Bryam Vargas , Vladimir Oltean , Victor Nogueira , Jamal Hadi Salim , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15.y] net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked Date: Tue, 28 Jul 2026 15:30:17 -0400 Message-ID: <20260728193017.455869-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026072146-curable-untreated-02d2@gregkh> References: <2026072146-curable-untreated-02d2@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Bryam Vargas [ Upstream commit e056e1dfcddca877dd46d704e8ec9860cfc9ec44 ] When taprio's software path peeks a non-work-conserving child qdisc, the child stashes the peeked skb in its gso_skb; taprio_dequeue_from_txq() then takes the packet with a direct child ->dequeue() call, which ignores that stash, orphans the peeked skb and desyncs the child's qlen/backlog. With a qfq child this re-enters the child on an emptied list and dereferences NULL, panicking the kernel from softirq on ordinary egress. Take the packet through qdisc_dequeue_peeked(), as sch_red and sch_sfb now do. The helper returns the child's stashed skb first and is a no-op when there is none, so a work-conserving child is unaffected and the gated path now consumes the skb whose length was charged to the budget. Fixes: 5a781ccbd19e ("tc: Add support for configuring the taprio scheduler") Cc: stable@vger.kernel.org Cc: Vladimir Oltean Signed-off-by: Bryam Vargas Reviewed-by: Victor Nogueira Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260625-b4-disp-31bcb279-v1-1-85c40b83c529@proton.me Signed-off-by: Jakub Kicinski [ applied the peek/dequeue conversion to both `child->ops->dequeue(child)` call sites, since 6.1 lacks the upstream cleanup that merged them into one ] Signed-off-by: Sasha Levin --- net/sched/sch_taprio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 8e7c0a3034cc41..9e6a1e0f075e94 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -558,7 +558,7 @@ static struct sk_buff *taprio_dequeue_from_txq(struct Qdisc *sch, int txq, return NULL; if (TXTIME_ASSIST_IS_ENABLED(q->flags)) { - skb = child->ops->dequeue(child); + skb = qdisc_dequeue_peeked(child); if (!skb) return NULL; goto skb_found; @@ -589,7 +589,7 @@ static struct sk_buff *taprio_dequeue_from_txq(struct Qdisc *sch, int txq, atomic_sub_return(len, &entry->budget) < 0) return NULL; - skb = child->ops->dequeue(child); + skb = qdisc_dequeue_peeked(child); if (unlikely(!skb)) return NULL; -- 2.53.0