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 0E214272E53; Thu, 20 Aug 2026 16:33:36 +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=1787243617; cv=none; b=ZvHuTBBBviWJijVljx82p6D4Ret0QqXfvN9DdI5Cninc91Qqt/CX9R7MD/oNhQfUoZfyyM+Leb9FZb4Mx/+49iE9OsaTfXcGh3KjAChZhLnnuAG99xwQo3RJ5siDedjj08hKWTIkeOdrzkbaDODbXWyZEoNk+MZNiV0DXCiwfXo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787243617; c=relaxed/simple; bh=3nB+Cyf3NcI8mhJvGCpy2Fi9BJnnMWTl8r/dElBLv0s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ACufLrQ1/mjJJfh0YA+U4w9no7UJxp/wKTNHyC5UaW3NpBEBeK3yc9K4PsNuN7mrdDmkChoXL3t4ywPIVAp6aZw0BHZ9UimNbJO9BqTmLi7fYFv2O7MNOV/WE7m5mpmDJVqE09T8piltBINkFhj00hiy8AHohNXRNe9wNfNF2MQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=N2uoptKn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="N2uoptKn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 703871F000E9; Thu, 20 Aug 2026 16:33:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787243616; bh=fu0CiuZ5jQt+9EaiTUI7wo2M9Coh2sRrJud5TQ9juy0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=N2uoptKnUWn5B9ZR3Aubf++nGsAO0DQnKcayEpl4CyOofpggu6y4efy705F7Ygcj2 K5VMoqqJcAVLgRFJH5Oj9iWsRnSpcFJ/AZzXJT961o3cgwlK1g++fmzfyok/X600h4 Nv2biET4KkejVEOLwlIKOlGXgW2/L2SZMpri2CXQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vladimir Oltean , Bryam Vargas , Victor Nogueira , Jamal Hadi Salim , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 154/272] net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked Date: Thu, 20 Aug 2026 16:55:38 +0200 Message-ID: <20260820145235.931416710@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145231.229664293@linuxfoundation.org> References: <20260820145231.229664293@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_taprio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -586,7 +586,7 @@ static struct sk_buff *taprio_dequeue_fr return NULL; skip_peek_checks: - skb = child->ops->dequeue(child); + skb = qdisc_dequeue_peeked(child); if (unlikely(!skb)) return NULL;