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 3424150EBE2; Wed, 30 Sep 2026 16:20:00 +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=1790785204; cv=none; b=rCq2tfwLw+oQyz0shmA8nkes1EkG8IMk5ngCmYLUFvhd83bTS18pT8HH+PY5ZMZXgSOmknGk4999SNBj8425ibJ8KbGEi16nFjjbNy3x/IIC5z5DWpGMJJiY8N8eWqCktYgIG4T1y3blaXNgEm0ZnjExQx3RLsvVGyMQDFGeorc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790785204; c=relaxed/simple; bh=QPeeLvC06eEhFmPX3GFlWVPdCE22zmbXauYP93hl0qw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=o1jcPBWEWUp1xiXUGTB4Hw7VB61h2pOcey7LuCejMZK7BiidXLFnLfGfaD2cRqYFbQ1dPcwhnXOKsvyd+gCbRB4dGQAkYn1BKr0Bpj81NuUgoFaIMvfw8KuZKyuP0gWdgxWtCZVrmQT6rSVNf99CoSmF+WeCLMfsNpgGGywDooc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=wKdnNUrY; 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="wKdnNUrY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37E341F00893; Wed, 30 Sep 2026 16:19:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790785197; bh=K4mctbxuHEohgSlayvV6fUAqWtenwjJs0BDy+U/m+rU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=wKdnNUrYS7lEjiu3/FBoJ5o/0UH5rZFO5Zuy1ymMLl3V/pr+AmGoqLn+rzpRli6p6 CuHc7MdqT07uDj5sinUGRHM2mWj2JfA/YMRduPq9bNHRTXXQ5NZTIvbo/6Um7XJJSI At2icyeKJgeBEAN5w3AvdbNEhbkCcW2hpJY2elCI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vega , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Victor Nogueira , Jamal Hadi Salim , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 424/982] net/sched: fq_pie: clamp quantum in change path Date: Wed, 30 Sep 2026 17:19:20 +0200 Message-ID: <20260930152425.909293870@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152416.775402466@linuxfoundation.org> References: <20260930152416.775402466@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jamal Hadi Salim [ Upstream commit 4864f58c53eb47257d55e01f47d4a9f355f7f970 ] fq_pie_change() accepts any quantum value from userspace, including 1. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times under the qdisc lock (a soft lockup / denial of service). Add max(256U, ...) matching fq_codel_change(). Conditions to recreate the bug: CONFIG_NET_SCH_FQ_PIE=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root fq_pie tc qdisc change dev dummy0 root fq_pie quantum 1 stab data 32768 size_log 15 cell_log 0 Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler") Reported-by: Vega Reviewed-by: Toke Høiland-Jørgensen Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/QDISC-0CFC.v3.20260901204856@mojatatu.com.3 Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_fq_pie.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c index f8fb1d1af6abb..75d6e7716ae8e 100644 --- a/net/sched/sch_fq_pie.c +++ b/net/sched/sch_fq_pie.c @@ -339,7 +339,8 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt, nla_get_u32(tb[TCA_FQ_PIE_BETA])); if (tb[TCA_FQ_PIE_QUANTUM]) - WRITE_ONCE(q->quantum, nla_get_u32(tb[TCA_FQ_PIE_QUANTUM])); + WRITE_ONCE(q->quantum, + max(256U, nla_get_u32(tb[TCA_FQ_PIE_QUANTUM]))); if (tb[TCA_FQ_PIE_MEMORY_LIMIT]) WRITE_ONCE(q->memory_limit, -- 2.53.0