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([2804:14d:5c5e:44fb:8ef6:cdff:1677:b083]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2c7e4ff8dcasm8999645a91.1.2024.06.24.08.55.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Jun 2024 08:55:43 -0700 (PDT) Message-ID: <06d0ea61-47ee-4e54-9dfa-a711c5bc07d0@mojatatu.com> Date: Mon, 24 Jun 2024 12:55:35 -0300 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] tracing/net_sched: NULL pointer dereference in perf_trace_qdisc_reset() To: Yunseong Kim Cc: netdev@vger.kernel.org, stable@vger.kernel.org, Jakub Kicinski , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Takashi Iwai , "David S. Miller" , =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , "Rafael J. Wysocki" , Jamal Hadi Salim , Cong Wang , Jiri Pirko , Eric Dumazet , Paolo Abeni , Taehee Yoo , Austin Kim , shjy180909@gmail.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, ppbuk5246@gmail.com, Yeoreum Yun References: <20240622045701.8152-2-yskelg@gmail.com> Content-Language: en-US From: Pedro Tammela In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 24/06/2024 12:43, Yunseong Kim wrote: > Hi Pedro, > > On 6/25/24 12:12 오전, Pedro Tammela wrote: >> On 22/06/2024 01:57, yskelg@gmail.com wrote: >>> From: Yunseong Kim >>> >>> In the TRACE_EVENT(qdisc_reset) NULL dereference occurred from >>> >>>   qdisc->dev_queue->dev ->name >>> >>> [ 5301.595872] KASAN: null-ptr-deref in range >>> [0x0000000000000130-0x0000000000000137] >>> [ 5301.595877] Mem abort info: >>> [ 5301.595881]   ESR = 0x0000000096000006 >>> [ 5301.595885]   EC = 0x25: DABT (current EL), IL = 32 bits >>> [ 5301.595889]   SET = 0, FnV = 0 >>> [ 5301.595893]   EA = 0, S1PTW = 0 >>> [ 5301.595896]   FSC = 0x06: level 2 translation fault >>> [ 5301.595900] Data abort info: >>> [ 5301.595903]   ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000 >>> [ 5301.595907]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0 >>> [ 5301.595911]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 >>> [ 5301.595915] [dfff800000000026] address between user and kernel >>> address ranges >>> [ 5301.595971] Internal error: Oops: 0000000096000006 [#1] SMP >>> Link: >>> https://lore.kernel.org/lkml/20240229143432.273b4871@gandalf.local.home/t/ >>> Fixes: 51270d573a8d ("tracing/net_sched: Fix tracepoints that save >>> qdisc_dev() as a string") >>> Cc: netdev@vger.kernel.org >>> Cc: stable@vger.kernel.org # +v6.7.10, +v6.8 >>> Signed-off-by: Yunseong Kim >>> Signed-off-by: Yeoreum Yun >>> --- >>>   include/trace/events/qdisc.h | 2 +- >>>   1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h >>> index f1b5e816e7e5..170b51fbe47a 100644 >>> --- a/include/trace/events/qdisc.h >>> +++ b/include/trace/events/qdisc.h >>> @@ -81,7 +81,7 @@ TRACE_EVENT(qdisc_reset, >>>       TP_ARGS(q), >>>         TP_STRUCT__entry( >>> -        __string(    dev,        qdisc_dev(q)->name    ) >>> +        __string(dev, qdisc_dev(q) ? qdisc_dev(q)->name : "noop_queue") >>>           __string(    kind,        q->ops->id        ) >>>           __field(    u32,        parent            ) >>>           __field(    u32,        handle            ) >> >> You missed the __assign_str portion (see below). Also let's just say >> "(null)" as it's the correct device name. "noop_queue" could be misleading. > > Thanks for the code review Pedro, I agree your advice. > >> diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h >> index 1f4258308b96..f54e0b4dbcf4 100644 >> --- a/include/trace/events/qdisc.h >> +++ b/include/trace/events/qdisc.h >> @@ -81,14 +81,14 @@ TRACE_EVENT(qdisc_reset, >>         TP_ARGS(q), >> >>         TP_STRUCT__entry( >> -               __string(       dev,            qdisc_dev(q)->name      ) >> +               __string(       dev,            qdisc_dev(q) ? >> qdisc_dev(q)->name : "(null)"    ) >>                 __string(       kind,           q->ops->id              ) >>                 __field(        u32,            parent                  ) >>                 __field(        u32,            handle                  ) >>         ), > > It looks better to align the name with the current convention. > > Link: > https://lore.kernel.org/linux-trace-kernel/20240222211442.634192653@goodmis.org/ > >>         TP_fast_assign( >> -               __assign_str(dev, qdisc_dev(q)->name); >> +               __assign_str(dev, qdisc_dev(q) ? qdisc_dev(q)->name : >> "(null)"); >>                 __assign_str(kind, q->ops->id); >>                 __entry->parent = q->parent; >>                 __entry->handle = q->handle; >> >> > > The second part you mentioned, Steve recently worked on it and changed it. > > Link: > https://lore.kernel.org/linux-trace-kernel/20240516133454.681ba6a0@rorschach.local.home/ Oh! > > If it hadn't, I don't think I would have been able to prevent the panic > by just applying my patch. But you must be careful with the backports. In any case, perhaps send another patch to net-next updating the new conventions there and use the 'old convention' for the bug fix?