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 03BC33B442B for ; Tue, 28 Jul 2026 18:06:41 +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=1785262003; cv=none; b=E/zFb4YNI7z5Jp7B3UdwiAgso7b8aP10RWBEJgz0eWNSE4/WSdEZzKU5O4rNyxrrUkKHuCszgR4pKcnaw6V4ENTAHS73PWtqqns/Jsf+JGBujpU71tCXE/CMK28bevlDxN6CNq9FK5ITDY8dRsoyDMj7kVM9bNPPngBN2gt775s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785262003; c=relaxed/simple; bh=D+ZnbpKUhAABnCbB2n826RqvdWKSyGulFPDq+Oeu62s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=S8tPehbIbnQGwTeESBDbdKQvlEHkvoRQQeVGXWJPq0cAfZQ2FapU8wRle9k5E9hccQcrL5XgDu7gDrfvJouQ/zVswo4G2oYipNmOBOZvCe/8YrBQ9wJ5eI65cGM5iDnLdT1mwDR9S+vcQYNQBEKkGUWjDEYb5w9klBB5U/NWyrs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Qc+GqvYA; 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="Qc+GqvYA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC5B01F00A3A; Tue, 28 Jul 2026 18:06:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785261998; bh=uxHhATtVgG2+ofiLqEF5McmvqZY5A+mF8bZ479TtWEA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Qc+GqvYAGMtp6IPWk3tORi/pXqcPwv1rqiG58ASeX7SSbhz0p8BYxuSFYl7eov9Uc DznXmJyBQi40qzSZ9KA9vYWxL9HxPQiPTZzxkkGe+fGQjXhkUz2cxGU82vzS3qg31G RAtYmDze2eXb9btBMehTuqSTSieuKMSNJYybqzB6l3+SYzpjuyMRJEtC/qmoYT780M E/w0U5wuXmBAjCX1MLwgoul9pBMpOAewIgjLrNGavHNSZd+q0Q0rEFoFI6yMUPmTVQ tQRYn+Dtrbj6iEXMJtqLFgJ3i1/z/WgHmMTU+2mM0n6lLZgsYJCdmXowmt0nuMGTNO p9nx9DPNbtumQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Bryam Vargas , Vladimir Oltean , Victor Nogueira , Jamal Hadi Salim , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1.y 2/2] net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked Date: Tue, 28 Jul 2026 14:06:35 -0400 Message-ID: <20260728180635.289503-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260728180635.289503-1-sashal@kernel.org> References: <2026072145-tank-retrain-5dd2@gregkh> <20260728180635.289503-1-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 299cad8ece93ba..6d1c83a076cd4a 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -596,7 +596,7 @@ 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