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Sat, 05 Jul 2025 20:07:33 -0700 (PDT) Received: from localhost ([2601:647:6881:9060:357d:7cd8:b68f:6a2a]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-74ce35cba78sm5919529b3a.57.2025.07.05.20.07.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Jul 2025 20:07:33 -0700 (PDT) Date: Sat, 5 Jul 2025 20:07:32 -0700 From: Cong Wang To: Xiang Mei Cc: netdev@vger.kernel.org, gregkh@linuxfoundation.org, jhs@mojatatu.com, jiri@resnulli.us, security@kernel.org Subject: Re: [PATCH v3] net/sched: sch_qfq: Fix null-deref in agg_dequeue Message-ID: References: <20250705212143.3982664-1-xmei5@asu.edu> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250705212143.3982664-1-xmei5@asu.edu> On Sat, Jul 05, 2025 at 02:21:43PM -0700, Xiang Mei wrote: > To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c) > when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return > value before using it, similar to the existing approach in sch_hfsc.c. > > To avoid code duplication, the following changes are made: > > 1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static > inline function. > > 2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to > include/net/pkt_sched.h so that sch_qfq can reuse it. > > 3. Applied qdisc_peek_len in agg_dequeue to avoid crashing. > > Signed-off-by: Xiang Mei Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost") Reviewed-by: Cong Wang Thanks!