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 0F13833D4F8 for ; Tue, 28 Jul 2026 18:07:14 +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=1785262036; cv=none; b=oGj9N5xPM9h1FEr+kO1GNt9XHpy+cooKm1WHNrnF1UBna+LZqLLGcKx0gCpA4WeDiX17ksgZrXsXoJV8Jq4DuUE86unS3GUqtK1remxhlxvcmG2q/Z8PdJcZja0f6bUWeoFeEjNGf6lnzKR5U25yoIVP+TcXVCiSSU3U0q7YexI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785262036; c=relaxed/simple; bh=tevHsckvkNw962WbEXR009cJzTdy8ZvSU5+IxodLd9U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=utOun27O0kQDrwwzsJg3hCeEskgGqAPoavPaUEYSdE+qsnr5D47ka5TPCAJYgUHSfye0gG8NkbSXGYJzPlawBPYJmeLHC72noqlE7sGNf0cheD73ka/WpZL7AQJayAMuNm+WFUqZ9UPgCoLv+Kvw+uxd94ZnmPAw0cCYO7L8Yxw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=k9P9TZLs; 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="k9P9TZLs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62AAE1F000E9; Tue, 28 Jul 2026 18:07:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785262034; bh=0qtUr+1RGAITd54o0ZsrzCgc8X4p4HcX9Tcu/+8wsZk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=k9P9TZLsThRUnBb+a5d8EcRga4hlQklgRyadRQd3PD1liWaot2jB/TZNKEVvGhcMD UZo+RprDplKSFnBG1zp4y9htR45fu57D82c+KszUt+9iQKH9N49LFKDKVxYww/xzxJ Kyx5Y34Y33ZS3Sb9wb/eibTWayqWIzJKZAqtA9hoiC6FHWMukKG32WXBiGXpC5D7Ru Wj18PjRKeUZJg7zJC6hi+FF+Uc/jLyHHxUS/84ixakydnEx4kBDMLqZdIvypN/llT/ aJXSxwRSoBRaXHSCpTBPMTu3CLuBzL4AgY80nMbwSqgGBH4fx2VmKuiT7cTUydLHKf 2KFZchLNk6t8g== 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] net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked Date: Tue, 28 Jul 2026 14:07:11 -0400 Message-ID: <20260728180711.291113-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026072145-tank-retrain-5dd2@gregkh> References: <2026072145-tank-retrain-5dd2@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 8da723f054f564..ea9c7aaf0885c4 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -568,7 +568,7 @@ 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; @@ -599,7 +599,7 @@ 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