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 D98DA3B992C for ; Tue, 28 Jul 2026 22:17:41 +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=1785277063; cv=none; b=KWUbDN5Bx5hQzKfF0jxuIpXUnHCxS2QORbMUKPT6fzaNuBNRau87WsIMFFSLfQU9Mv0UvD7wQXwfYLDCfeqtvdjr7VRZzN15q2OFxzg3mnKu/I6POG1cMgG7V0lVBSOWKvomh97V6km4EE4x1y0/ij3+Ic0czPzBPkQ5d1zZDvY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785277063; c=relaxed/simple; bh=lIE0eak4UMyQWfbDefr95FH/rBKiDyyiSVwL3upfkPU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ArCRkGCK8+NDgWF8QlcrhKmnfd2NvlMocrIres1c1Nrq1zlx66PJD9JXoFFmOwL8NATaZLryVvygHLhAfPAzOMTjEMQSZqG/ZDpVw5zuFW1G+A9mTH9PgCDE8USml+Z/+atpvYg2x+uoc0Yzmf1zlkENibQoaO5+M93QbgFoDIc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IBmjNX9h; 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="IBmjNX9h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 159211F00A3D; Tue, 28 Jul 2026 22:17:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785277061; bh=/PvClSVNwBh1HwYnVk5Ssu+1qEkAv32ouYxM2Dhj5H4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IBmjNX9h+SRID1jRiHKhLj0cVcrzWFUQZWMY3oQcJdPHf+um0a0ImbTHvJ6f8Xfny mFzePHqV9ZTsMXxh9s9Op7AZY3yxTNK4Pp1vHVPA1Eo/FZfWxe9qF2GnbYhAGuQ9Yd OpcbVnMk33txD9FZT0piXa8bJ+RH3h33hYsjmfvgcBMtqw6IoSyldPWGrOG2PSm6ot U6fMmYYzFu02xgk6O1GFHAsHtBuTtRFb0Zywi10RMQgf4g1G5KLBpC2XqRZGWvul+H IEXfZaACh2zP/JiwtyUoPE5lIHKjwZFYUcH3D3jodSkPAw8wpLkACgbdMwZVYwzSPc pb5iaB4f5q1Dw== From: Sasha Levin To: stable@vger.kernel.org Cc: Bryam Vargas , Vladimir Oltean , Victor Nogueira , Jamal Hadi Salim , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.10.y 2/2] net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked Date: Tue, 28 Jul 2026 18:17:38 -0400 Message-ID: <20260728221738.745743-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260728221738.745743-1-sashal@kernel.org> References: <2026072146-reclusive-rocky-a67e@gregkh> <20260728221738.745743-1-sashal@kernel.org> 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 Signed-off-by: Sasha Levin --- net/sched/sch_taprio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 237e4a16a0e505..d0b25ab5ff9aa1 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -588,7 +588,7 @@ static struct sk_buff *taprio_dequeue_from_txq(struct Qdisc *sch, int txq, return NULL; skip_peek_checks: - skb = child->ops->dequeue(child); + skb = qdisc_dequeue_peeked(child); if (unlikely(!skb)) return NULL; -- 2.53.0