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Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , Jamal Hadi Salim , Jiri Pirko , netdev@vger.kernel.org, eric.dumazet@gmail.com, Gerrard Tai , stable@vger.kernel.org Subject: Re: [PATCH net] net_sched: sch_sfq: reject invalid perturb period Message-ID: References: <20250611083501.1810459-1-edumazet@google.com> 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: <20250611083501.1810459-1-edumazet@google.com> On Wed, Jun 11, 2025 at 08:35:01AM +0000, Eric Dumazet wrote: > Gerrard Tai reported that SFQ perturb_period has no range check yet, > and this can be used to trigger a race condition fixed in a separate patch. > > We want to make sure ctl->perturb_period * HZ will not overflow > and is positive. > > Tested: > > tc qd add dev lo root sfq perturb -10 # negative value : error > Error: sch_sfq: invalid perturb period. > > tc qd add dev lo root sfq perturb 1000000000 # too big : error > Error: sch_sfq: invalid perturb period. > > tc qd add dev lo root sfq perturb 2000000 # acceptable value > tc -s -d qd sh dev lo > qdisc sfq 8005: root refcnt 2 limit 127p quantum 64Kb depth 127 flows 128 divisor 1024 perturb 2000000sec > Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) > backlog 0b 0p requeues 0 Please kindly provide a selftest (as a separate patch) since it looks fairly easy to reproduce. 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