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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: Yunseong Kim In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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/ If it hadn't, I don't think I would have been able to prevent the panic by just applying my patch. Link: https://lore.kernel.org/all/e2f9da4e-919d-4a98-919d-167726ef6bc7@gmail.com/ Warm Regards, Yunseong Kim