* [PATCH] usb: mtu3: Fix double dereference in TP_printk
@ 2026-09-22 10:37 Vladimir Murzin
2026-09-28 13:11 ` Vladimir Murzin
0 siblings, 1 reply; 3+ messages in thread
From: Vladimir Murzin @ 2026-09-22 10:37 UTC (permalink / raw)
To: linux-usb
Cc: linux-arm-kernel, linux-mediatek, linux-kernel, chunfeng.yun,
gregkh, rostedt, paulmck, mark.rutland, Vladimir Murzin
Paul reported kernel splat:
[ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
[ 0.000000] WARNING: kernel/trace/trace_events.c:420 at test_double_dereference+0x144/0x14c, CPU#0: swapper/0/0
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.3.0-rc1 #15247 PREEMPT
[ 0.000000] Hardware name: linux,dummy-virt (DT)
[ 0.000000] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 0.000000] pc : test_double_dereference+0x144/0x14c
[ 0.000000] lr : test_double_dereference+0x144/0x14c
[ 0.000000] sp : ffffc80aa7633bf0
[ 0.000000] x29: ffffc80aa7633bf0 x28: ffffc80aa7c0f047 x27: 000508b58019388f
[ 0.000000] x26: 0000000000000003 x25: 0000000000000007 x24: ffffc80aa5fceff8
[ 0.000000] x23: ffffc80aa7c0f05a x22: ffffc80aa64edfe8 x21: ffffc80aa7c0fce8
[ 0.000000] x20: ffffc80aa7c0f047 x19: 0000000000000013 x18: 0000000000000001
[ 0.000000] x17: 6572656420656c62 x16: 756f642073616820 x15: 746c61685f746573
[ 0.000000] x14: 0000000000000000 x13: ffff000139d90000 x12: 0000000000000045
[ 0.000000] x11: 00000000000000cf x10: ffff00013f546428 x9 : ffff000139d90000
[ 0.000000] x8 : 3fffffffffffc000 x7 : 0000000000000001 x6 : 0000000000000001
[ 0.000000] x5 : ffff00013f4e6440 x4 : 0000000000000000 x3 : 0000000000000000
[ 0.000000] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffc80aa764a700
[ 0.000000] Call trace:
[ 0.000000] test_double_dereference+0x144/0x14c (P)
[ 0.000000] trace_event_raw_init+0x37c/0x5d8
[ 0.000000] event_init+0x34/0xc0
[ 0.000000] trace_event_init+0xec/0x588
[ 0.000000] trace_init+0x24/0x6e0
[ 0.000000] start_kernel+0x4a0/0x8ec
[ 0.000000] __primary_switched+0x88/0x90
[ 0.000000] irq event stamp: 0
[ 0.000000] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[ 0.000000] hardirqs last disabled at (0): [<0000000000000000>] 0x0
[ 0.000000] softirqs last enabled at (0): [<0000000000000000>] 0x0
[ 0.000000] softirqs last disabled at (0): [<0000000000000000>] 0x0
[ 0.000000] ---[ end trace 0000000000000000 ]---
[ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_disable has double dereference in TP_printk: &REC->gpd_ring->dma
[ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_enable has double dereference in TP_printk: &REC->gpd_ring->dma
Which also observed by Mark and myself.
The splat it result of new check introduced by b5cc230af5e5 ("tracing:
Warn when an event dereferences a pointer in TP_printk()") which
correctly catches issue with %pad dereferencing the address saved in
the ring buffer. TP_fast_assign() logic gets executed when the
tracepoint is triggered, however the TP_printk() is executed when the
user reads the trace buffer which could be seconds, minutes, hours,
days, even months later and nothing guarantee that __entry->gpd_ring
pointer will still be pointing to what it was when it was recorded.
Fix the issue by capturing immediate value of gpd_ring.dma when trace
point is triggered.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
drivers/usb/mtu3/mtu3_trace.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/mtu3/mtu3_trace.h b/drivers/usb/mtu3/mtu3_trace.h
index 89870175d635..9aaa167d69c1 100644
--- a/drivers/usb/mtu3/mtu3_trace.h
+++ b/drivers/usb/mtu3/mtu3_trace.h
@@ -224,6 +224,7 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
__field(unsigned int, flags)
__field(unsigned int, direction)
__field(struct mtu3_gpd_ring *, gpd_ring)
+ __field(dma_addr_t, gpd_ring_dma)
),
TP_fast_assign(
__assign_str(name);
@@ -235,12 +236,13 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
__entry->flags = mep->flags;
__entry->direction = mep->is_in;
__entry->gpd_ring = &mep->gpd_ring;
+ __entry->gpd_ring_dma = mep->gpd_ring.dma
),
TP_printk("%s: type %s maxp %d slot %d mult %d burst %d ring %p/%pad flags %c:%c%c%c:%c",
__get_str(name), usb_ep_type_string(__entry->type),
__entry->maxp, __entry->slot,
__entry->mult, __entry->maxburst,
- __entry->gpd_ring, &__entry->gpd_ring->dma,
+ __entry->gpd_ring, &__entry->gpd_ring_dma,
__entry->flags & MTU3_EP_ENABLED ? 'E' : 'e',
__entry->flags & MTU3_EP_STALL ? 'S' : 's',
__entry->flags & MTU3_EP_WEDGE ? 'W' : 'w',
--
2.34.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] usb: mtu3: Fix double dereference in TP_printk
2026-09-22 10:37 [PATCH] usb: mtu3: Fix double dereference in TP_printk Vladimir Murzin
@ 2026-09-28 13:11 ` Vladimir Murzin
2026-09-28 18:21 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: Vladimir Murzin @ 2026-09-28 13:11 UTC (permalink / raw)
To: linux-usb
Cc: linux-arm-kernel, linux-mediatek, linux-kernel, chunfeng.yun,
gregkh, rostedt, paulmck, mark.rutland
Hi All,
Gentle ping... spat is still present in v7.3-rc5
Cheers
Vladimir
On 9/22/26 11:37, Vladimir Murzin wrote:
> Paul reported kernel splat:
>
> [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
> [ 0.000000] ------------[ cut here ]------------
> [ 0.000000] Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
> [ 0.000000] WARNING: kernel/trace/trace_events.c:420 at test_double_dereference+0x144/0x14c, CPU#0: swapper/0/0
> [ 0.000000] Modules linked in:
> [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.3.0-rc1 #15247 PREEMPT
> [ 0.000000] Hardware name: linux,dummy-virt (DT)
> [ 0.000000] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 0.000000] pc : test_double_dereference+0x144/0x14c
> [ 0.000000] lr : test_double_dereference+0x144/0x14c
> [ 0.000000] sp : ffffc80aa7633bf0
> [ 0.000000] x29: ffffc80aa7633bf0 x28: ffffc80aa7c0f047 x27: 000508b58019388f
> [ 0.000000] x26: 0000000000000003 x25: 0000000000000007 x24: ffffc80aa5fceff8
> [ 0.000000] x23: ffffc80aa7c0f05a x22: ffffc80aa64edfe8 x21: ffffc80aa7c0fce8
> [ 0.000000] x20: ffffc80aa7c0f047 x19: 0000000000000013 x18: 0000000000000001
> [ 0.000000] x17: 6572656420656c62 x16: 756f642073616820 x15: 746c61685f746573
> [ 0.000000] x14: 0000000000000000 x13: ffff000139d90000 x12: 0000000000000045
> [ 0.000000] x11: 00000000000000cf x10: ffff00013f546428 x9 : ffff000139d90000
> [ 0.000000] x8 : 3fffffffffffc000 x7 : 0000000000000001 x6 : 0000000000000001
> [ 0.000000] x5 : ffff00013f4e6440 x4 : 0000000000000000 x3 : 0000000000000000
> [ 0.000000] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffc80aa764a700
> [ 0.000000] Call trace:
> [ 0.000000] test_double_dereference+0x144/0x14c (P)
> [ 0.000000] trace_event_raw_init+0x37c/0x5d8
> [ 0.000000] event_init+0x34/0xc0
> [ 0.000000] trace_event_init+0xec/0x588
> [ 0.000000] trace_init+0x24/0x6e0
> [ 0.000000] start_kernel+0x4a0/0x8ec
> [ 0.000000] __primary_switched+0x88/0x90
> [ 0.000000] irq event stamp: 0
> [ 0.000000] hardirqs last enabled at (0): [<0000000000000000>] 0x0
> [ 0.000000] hardirqs last disabled at (0): [<0000000000000000>] 0x0
> [ 0.000000] softirqs last enabled at (0): [<0000000000000000>] 0x0
> [ 0.000000] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [ 0.000000] ---[ end trace 0000000000000000 ]---
> [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_disable has double dereference in TP_printk: &REC->gpd_ring->dma
> [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_enable has double dereference in TP_printk: &REC->gpd_ring->dma
>
> Which also observed by Mark and myself.
>
> The splat it result of new check introduced by b5cc230af5e5 ("tracing:
> Warn when an event dereferences a pointer in TP_printk()") which
> correctly catches issue with %pad dereferencing the address saved in
> the ring buffer. TP_fast_assign() logic gets executed when the
> tracepoint is triggered, however the TP_printk() is executed when the
> user reads the trace buffer which could be seconds, minutes, hours,
> days, even months later and nothing guarantee that __entry->gpd_ring
> pointer will still be pointing to what it was when it was recorded.
>
> Fix the issue by capturing immediate value of gpd_ring.dma when trace
> point is triggered.
>
> Reported-by: Paul E. McKenney <paulmck@kernel.org>
> Tested-by: Mark Rutland <mark.rutland@arm.com>
> Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
> drivers/usb/mtu3/mtu3_trace.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/mtu3/mtu3_trace.h b/drivers/usb/mtu3/mtu3_trace.h
> index 89870175d635..9aaa167d69c1 100644
> --- a/drivers/usb/mtu3/mtu3_trace.h
> +++ b/drivers/usb/mtu3/mtu3_trace.h
> @@ -224,6 +224,7 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
> __field(unsigned int, flags)
> __field(unsigned int, direction)
> __field(struct mtu3_gpd_ring *, gpd_ring)
> + __field(dma_addr_t, gpd_ring_dma)
> ),
> TP_fast_assign(
> __assign_str(name);
> @@ -235,12 +236,13 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
> __entry->flags = mep->flags;
> __entry->direction = mep->is_in;
> __entry->gpd_ring = &mep->gpd_ring;
> + __entry->gpd_ring_dma = mep->gpd_ring.dma
> ),
> TP_printk("%s: type %s maxp %d slot %d mult %d burst %d ring %p/%pad flags %c:%c%c%c:%c",
> __get_str(name), usb_ep_type_string(__entry->type),
> __entry->maxp, __entry->slot,
> __entry->mult, __entry->maxburst,
> - __entry->gpd_ring, &__entry->gpd_ring->dma,
> + __entry->gpd_ring, &__entry->gpd_ring_dma,
> __entry->flags & MTU3_EP_ENABLED ? 'E' : 'e',
> __entry->flags & MTU3_EP_STALL ? 'S' : 's',
> __entry->flags & MTU3_EP_WEDGE ? 'W' : 'w',
> -- 2.34.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] usb: mtu3: Fix double dereference in TP_printk
2026-09-28 13:11 ` Vladimir Murzin
@ 2026-09-28 18:21 ` Paul E. McKenney
0 siblings, 0 replies; 3+ messages in thread
From: Paul E. McKenney @ 2026-09-28 18:21 UTC (permalink / raw)
To: Vladimir Murzin
Cc: linux-usb, linux-arm-kernel, linux-mediatek, linux-kernel,
chunfeng.yun, gregkh, rostedt, mark.rutland
On Mon, Sep 28, 2026 at 02:11:42PM +0100, Vladimir Murzin wrote:
> Hi All,
>
> Gentle ping... spat is still present in v7.3-rc5
If no one else wants to push it, I can do so. I gotta admit that the
resulting test failures when I forget to apply it are a bit annoying. ;-)
Thanx, Paul
> Cheers
> Vladimir
>
> On 9/22/26 11:37, Vladimir Murzin wrote:
> > Paul reported kernel splat:
> >
> > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
> > [ 0.000000] ------------[ cut here ]------------
> > [ 0.000000] Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
> > [ 0.000000] WARNING: kernel/trace/trace_events.c:420 at test_double_dereference+0x144/0x14c, CPU#0: swapper/0/0
> > [ 0.000000] Modules linked in:
> > [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.3.0-rc1 #15247 PREEMPT
> > [ 0.000000] Hardware name: linux,dummy-virt (DT)
> > [ 0.000000] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > [ 0.000000] pc : test_double_dereference+0x144/0x14c
> > [ 0.000000] lr : test_double_dereference+0x144/0x14c
> > [ 0.000000] sp : ffffc80aa7633bf0
> > [ 0.000000] x29: ffffc80aa7633bf0 x28: ffffc80aa7c0f047 x27: 000508b58019388f
> > [ 0.000000] x26: 0000000000000003 x25: 0000000000000007 x24: ffffc80aa5fceff8
> > [ 0.000000] x23: ffffc80aa7c0f05a x22: ffffc80aa64edfe8 x21: ffffc80aa7c0fce8
> > [ 0.000000] x20: ffffc80aa7c0f047 x19: 0000000000000013 x18: 0000000000000001
> > [ 0.000000] x17: 6572656420656c62 x16: 756f642073616820 x15: 746c61685f746573
> > [ 0.000000] x14: 0000000000000000 x13: ffff000139d90000 x12: 0000000000000045
> > [ 0.000000] x11: 00000000000000cf x10: ffff00013f546428 x9 : ffff000139d90000
> > [ 0.000000] x8 : 3fffffffffffc000 x7 : 0000000000000001 x6 : 0000000000000001
> > [ 0.000000] x5 : ffff00013f4e6440 x4 : 0000000000000000 x3 : 0000000000000000
> > [ 0.000000] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffc80aa764a700
> > [ 0.000000] Call trace:
> > [ 0.000000] test_double_dereference+0x144/0x14c (P)
> > [ 0.000000] trace_event_raw_init+0x37c/0x5d8
> > [ 0.000000] event_init+0x34/0xc0
> > [ 0.000000] trace_event_init+0xec/0x588
> > [ 0.000000] trace_init+0x24/0x6e0
> > [ 0.000000] start_kernel+0x4a0/0x8ec
> > [ 0.000000] __primary_switched+0x88/0x90
> > [ 0.000000] irq event stamp: 0
> > [ 0.000000] hardirqs last enabled at (0): [<0000000000000000>] 0x0
> > [ 0.000000] hardirqs last disabled at (0): [<0000000000000000>] 0x0
> > [ 0.000000] softirqs last enabled at (0): [<0000000000000000>] 0x0
> > [ 0.000000] softirqs last disabled at (0): [<0000000000000000>] 0x0
> > [ 0.000000] ---[ end trace 0000000000000000 ]---
> > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_disable has double dereference in TP_printk: &REC->gpd_ring->dma
> > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_enable has double dereference in TP_printk: &REC->gpd_ring->dma
> >
> > Which also observed by Mark and myself.
> >
> > The splat it result of new check introduced by b5cc230af5e5 ("tracing:
> > Warn when an event dereferences a pointer in TP_printk()") which
> > correctly catches issue with %pad dereferencing the address saved in
> > the ring buffer. TP_fast_assign() logic gets executed when the
> > tracepoint is triggered, however the TP_printk() is executed when the
> > user reads the trace buffer which could be seconds, minutes, hours,
> > days, even months later and nothing guarantee that __entry->gpd_ring
> > pointer will still be pointing to what it was when it was recorded.
> >
> > Fix the issue by capturing immediate value of gpd_ring.dma when trace
> > point is triggered.
> >
> > Reported-by: Paul E. McKenney <paulmck@kernel.org>
> > Tested-by: Mark Rutland <mark.rutland@arm.com>
> > Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
> > Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> > ---
> > drivers/usb/mtu3/mtu3_trace.h | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/mtu3/mtu3_trace.h b/drivers/usb/mtu3/mtu3_trace.h
> > index 89870175d635..9aaa167d69c1 100644
> > --- a/drivers/usb/mtu3/mtu3_trace.h
> > +++ b/drivers/usb/mtu3/mtu3_trace.h
> > @@ -224,6 +224,7 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
> > __field(unsigned int, flags)
> > __field(unsigned int, direction)
> > __field(struct mtu3_gpd_ring *, gpd_ring)
> > + __field(dma_addr_t, gpd_ring_dma)
> > ),
> > TP_fast_assign(
> > __assign_str(name);
> > @@ -235,12 +236,13 @@ DECLARE_EVENT_CLASS(mtu3_log_ep,
> > __entry->flags = mep->flags;
> > __entry->direction = mep->is_in;
> > __entry->gpd_ring = &mep->gpd_ring;
> > + __entry->gpd_ring_dma = mep->gpd_ring.dma
> > ),
> > TP_printk("%s: type %s maxp %d slot %d mult %d burst %d ring %p/%pad flags %c:%c%c%c:%c",
> > __get_str(name), usb_ep_type_string(__entry->type),
> > __entry->maxp, __entry->slot,
> > __entry->mult, __entry->maxburst,
> > - __entry->gpd_ring, &__entry->gpd_ring->dma,
> > + __entry->gpd_ring, &__entry->gpd_ring_dma,
> > __entry->flags & MTU3_EP_ENABLED ? 'E' : 'e',
> > __entry->flags & MTU3_EP_STALL ? 'S' : 's',
> > __entry->flags & MTU3_EP_WEDGE ? 'W' : 'w',
> > -- 2.34.1
> >
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-09-28 18:21 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2026-09-22 10:37 [PATCH] usb: mtu3: Fix double dereference in TP_printk Vladimir Murzin
2026-09-28 13:11 ` Vladimir Murzin
2026-09-28 18:21 ` Paul E. McKenney
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