From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 536F6350D7B; Tue, 26 Aug 2025 14:28:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756218524; cv=none; b=rFsLT/ytRqZzRxyIFyMW0be3zWVJAdCDBrM6YKP2GmJFtD9mexO83u8h1A9mbBXiBsRkaPjnIJ98ZQQrUBheXNX8mz2Nu7+JE224b37v9f6linrWrDMCV7oygX0GLi1bMiurCMHBc2X2003puHUSOEnP6BXBl5bCxovjTPxpIug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756218524; c=relaxed/simple; bh=g3U+DKNokvO0aULl4qewBZiuNiENhCozaD+VLnhrzBU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Zz12kWmrcufquajkR0dyhBe2cY7XI8ZjLkd0EPNkyDg6u0IkZt7xyYbuhGFuKiWc+GxHHflYzLP9h6FHUgjWvgq9D03O8jY+Tfwb74jHh/863KjEydLMfq/4tSeGk1M7XsNB/JAdt0IWNjiO0GBHxDYKSLf8r87Uow5QKd03+vo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KOWoIygr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="KOWoIygr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D64DC4CEF1; Tue, 26 Aug 2025 14:28:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756218522; bh=g3U+DKNokvO0aULl4qewBZiuNiENhCozaD+VLnhrzBU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KOWoIygrfxgYeV0aWk+B1e7BDVM8QstmFn7D5Le770CuQjz6oqBBZ9y2t6ApDGt8X FQgtT2j2B/o/61CRthAQ5Lcl3r8lerkRoxB8ODtIGXGnJFn4AMBdMmoaZLUqnpSMkv Z5P1+4QE+9qeQo4jHdmhcKEEGX2Rx9IkJzvmLNfc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiang Mei , Cong Wang , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 032/403] net/sched: sch_qfq: Fix race condition on qfq_aggregate Date: Tue, 26 Aug 2025 13:05:58 +0200 Message-ID: <20250826110906.701306665@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110905.607690791@linuxfoundation.org> References: <20250826110905.607690791@linuxfoundation.org> User-Agent: quilt/0.68 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-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei [ Upstream commit 5e28d5a3f774f118896aec17a3a20a9c5c9dfc64 ] A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free. This patch addresses the issue by: 1. Moved qfq_destroy_class into the critical section. 2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats. Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost") Signed-off-by: Xiang Mei Reviewed-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sched/sch_qfq.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index c466d255f7865..2a4331a084949 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -408,7 +408,7 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, bool existing = false; struct nlattr *tb[TCA_QFQ_MAX + 1]; struct qfq_aggregate *new_agg = NULL; - u32 weight, lmax, inv_w; + u32 weight, lmax, inv_w, old_weight, old_lmax; int err; int delta_w; @@ -444,12 +444,16 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, inv_w = ONE_FP / weight; weight = ONE_FP / inv_w; - if (cl != NULL && - lmax == cl->agg->lmax && - weight == cl->agg->class_weight) - return 0; /* nothing to change */ + if (cl != NULL) { + sch_tree_lock(sch); + old_weight = cl->agg->class_weight; + old_lmax = cl->agg->lmax; + sch_tree_unlock(sch); + if (lmax == old_lmax && weight == old_weight) + return 0; /* nothing to change */ + } - delta_w = weight - (cl ? cl->agg->class_weight : 0); + delta_w = weight - (cl ? old_weight : 0); if (q->wsum + delta_w > QFQ_MAX_WSUM) { pr_notice("qfq: total weight out of range (%d + %u)\n", @@ -550,10 +554,10 @@ static int qfq_delete_class(struct Qdisc *sch, unsigned long arg) qdisc_purge_queue(cl->qdisc); qdisc_class_hash_remove(&q->clhash, &cl->common); + qfq_destroy_class(sch, cl); sch_tree_unlock(sch); - qfq_destroy_class(sch, cl); return 0; } @@ -620,6 +624,7 @@ static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, { struct qfq_class *cl = (struct qfq_class *)arg; struct nlattr *nest; + u32 class_weight, lmax; tcm->tcm_parent = TC_H_ROOT; tcm->tcm_handle = cl->common.classid; @@ -628,8 +633,13 @@ static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, nest = nla_nest_start_noflag(skb, TCA_OPTIONS); if (nest == NULL) goto nla_put_failure; - if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) || - nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax)) + + sch_tree_lock(sch); + class_weight = cl->agg->class_weight; + lmax = cl->agg->lmax; + sch_tree_unlock(sch); + if (nla_put_u32(skb, TCA_QFQ_WEIGHT, class_weight) || + nla_put_u32(skb, TCA_QFQ_LMAX, lmax)) goto nla_put_failure; return nla_nest_end(skb, nest); @@ -646,8 +656,10 @@ static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, memset(&xstats, 0, sizeof(xstats)); + sch_tree_lock(sch); xstats.weight = cl->agg->class_weight; xstats.lmax = cl->agg->lmax; + sch_tree_unlock(sch); if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), d, NULL, &cl->bstats) < 0 || -- 2.39.5