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 EC6C9364931; Wed, 30 Sep 2026 18:04:42 +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=1790791484; cv=none; b=X+SeeZhAseVFuuklifQr+QVMG1Hd81fYK+OTDw15G/KNdZwBfyYNrLN4NQLoi8MSgXlRDU++/DSNUGLHv76hPI1Sq/6g9FjSWDWRw9hlJuUt5LjwzSekDL8TrDegRFaakn7tmpViMDfq1RY0EF201Yw+117CMdG5FWGXwVejFuc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791484; c=relaxed/simple; bh=CDC+bPTCYl7tlJaQphfPfjnco7PAzoG/P2pZsu06DzE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=jXkzKEZXVKL4GHy2iy9nzEU+PbNurkk2ksS9IqD46U4nbWiBCQEYA73v2NI4oDD5J0uvKu/PVH5Hf0RBMAt5+J8sICjxG34GV5Yy9qqyQjsI0Ld9U88Wr9AWJoRmKrkNs1Qkh42L0ddK5HMSSmbhkOTNlstWpMG8LWGLukeEKVA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oZl9f+Yc; 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="oZl9f+Yc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58D291F000FF; Wed, 30 Sep 2026 18:04:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791482; bh=4RQCAmYfNbZjz4R8aYRxDaVjrtyJrJi/BBYwF+431L0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oZl9f+Yc/pi6FCjBfu/2/T8lh+l9IsitX2EZNGGM9BFJgcodJ2xiJE6Ty4AtPMk4W gi+F58ZxzdF3IynKfXiI7uVeTaICjZ9jKdSN/fHk3CsZyyRTasmteZtYV8z8lZIe1R GRvcUBf1vt5/EF0rxDDtb6AXDxZ90iHgl5uujvsU= 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 5.15 316/752] net/sched: fq_pie: clamp quantum in change path Date: Wed, 30 Sep 2026 17:23:06 +0200 Message-ID: <20260930152405.136493840@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@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 5.15-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 e3d9a92a1ba68..0d089d435db04 100644 --- a/net/sched/sch_fq_pie.c +++ b/net/sched/sch_fq_pie.c @@ -342,7 +342,8 @@ 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