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@xxxxxxxxx wrote:
From: Yunseong Kim <yskelg@xxxxxxxxx>
In the TRACE_EVENT(qdisc_reset) NULL dereference occurred from
qdisc->dev_queue->dev <NULL> ->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@xxxxxxxxxxxxxxxxxx/t/
Fixes: 51270d573a8d ("tracing/net_sched: Fix tracepoints that save
qdisc_dev() as a string")
Cc: netdev@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # +v6.7.10, +v6.8
Signed-off-by: Yunseong Kim <yskelg@xxxxxxxxx>
Signed-off-by: Yeoreum Yun <yeoreum.yun@xxxxxxx>
---
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@xxxxxxxxxxx/
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@xxxxxxxxxxxxxxxxxxxx/
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?
