* [PATCH] [PATCH v3] perf/x86/amd: check event before enable to avoid GPF
@ 2024-10-08 13:00 George Kennedy
2025-10-14 8:37 ` Peter Zijlstra
2025-10-16 9:33 ` [tip: perf/core] perf/x86/amd: Check " tip-bot2 for George Kennedy
0 siblings, 2 replies; 3+ messages in thread
From: George Kennedy @ 2024-10-08 13:00 UTC (permalink / raw)
To: ravi.bangoria
Cc: george.kennedy, harshit.m.mogalapalli, peterz, mingo, acme,
namhyung, mark.rutland, alexander.shishkin, jolsa, irogers,
adrian.hunter, kan.liang, tglx, bp, dave.hansen, x86, hpa,
linux-perf-users, linux-kernel, dongli.zhang, stable
On AMD machines cpuc->events[idx] can become NULL in a subtle race
condition with NMI->throttle->x86_pmu_stop().
Check event for NULL in amd_pmu_enable_all() before enable to avoid a GPF.
This appears to be an AMD only issue.
Syzkaller reported a GPF in amd_pmu_enable_all.
INFO: NMI handler (perf_event_nmi_handler) took too long to run: 13.143
msecs
Oops: general protection fault, probably for non-canonical address
0xdffffc0000000034: 0000 PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000001a0-0x00000000000001a7]
CPU: 0 UID: 0 PID: 328415 Comm: repro_36674776 Not tainted 6.12.0-rc1-syzk
RIP: 0010:x86_pmu_enable_event (arch/x86/events/perf_event.h:1195
arch/x86/events/core.c:1430)
RSP: 0018:ffff888118009d60 EFLAGS: 00010012
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000034 RSI: 0000000000000000 RDI: 00000000000001a0
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002
R13: ffff88811802a440 R14: ffff88811802a240 R15: ffff8881132d8601
FS: 00007f097dfaa700(0000) GS:ffff888118000000(0000) GS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200001c0 CR3: 0000000103d56000 CR4: 00000000000006f0
Call Trace:
<IRQ>
amd_pmu_enable_all (arch/x86/events/amd/core.c:760 (discriminator 2))
x86_pmu_enable (arch/x86/events/core.c:1360)
event_sched_out (kernel/events/core.c:1191 kernel/events/core.c:1186
kernel/events/core.c:2346)
__perf_remove_from_context (kernel/events/core.c:2435)
event_function (kernel/events/core.c:259)
remote_function (kernel/events/core.c:92 (discriminator 1)
kernel/events/core.c:72 (discriminator 1))
__flush_smp_call_function_queue (./arch/x86/include/asm/jump_label.h:27
./include/linux/jump_label.h:207 ./include/trace/events/csd.h:64
kernel/smp.c:135 kernel/smp.c:540)
__sysvec_call_function_single (./arch/x86/include/asm/jump_label.h:27
./include/linux/jump_label.h:207
./arch/x86/include/asm/trace/irq_vectors.h:99 arch/x86/kernel/smp.c:272)
sysvec_call_function_single (arch/x86/kernel/smp.c:266 (discriminator 47)
arch/x86/kernel/smp.c:266 (discriminator 47))
</IRQ>
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
---
Suggested comment now with the code.
arch/x86/events/amd/core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 920e3a640cad..6615ace15f5d 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -762,7 +762,12 @@ static void amd_pmu_enable_all(int added)
if (!test_bit(idx, cpuc->active_mask))
continue;
- amd_pmu_enable_event(cpuc->events[idx]);
+ /*
+ * FIXME: cpuc->events[idx] can become NULL in a subtle race
+ * condition with NMI->throttle->x86_pmu_stop().
+ */
+ if (cpuc->events[idx])
+ amd_pmu_enable_event(cpuc->events[idx]);
}
}
--
2.39.3
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] [PATCH v3] perf/x86/amd: check event before enable to avoid GPF
2024-10-08 13:00 [PATCH] [PATCH v3] perf/x86/amd: check event before enable to avoid GPF George Kennedy
@ 2025-10-14 8:37 ` Peter Zijlstra
2025-10-16 9:33 ` [tip: perf/core] perf/x86/amd: Check " tip-bot2 for George Kennedy
1 sibling, 0 replies; 3+ messages in thread
From: Peter Zijlstra @ 2025-10-14 8:37 UTC (permalink / raw)
To: George Kennedy
Cc: ravi.bangoria, harshit.m.mogalapalli, mingo, acme, namhyung,
mark.rutland, alexander.shishkin, jolsa, irogers, adrian.hunter,
kan.liang, tglx, bp, dave.hansen, x86, hpa, linux-perf-users,
linux-kernel, dongli.zhang, stable
On Tue, Oct 08, 2024 at 08:00:53AM -0500, George Kennedy wrote:
> On AMD machines cpuc->events[idx] can become NULL in a subtle race
> condition with NMI->throttle->x86_pmu_stop().
>
> Check event for NULL in amd_pmu_enable_all() before enable to avoid a GPF.
> This appears to be an AMD only issue.
>
> Syzkaller reported a GPF in amd_pmu_enable_all.
>
> INFO: NMI handler (perf_event_nmi_handler) took too long to run: 13.143
> msecs
> Oops: general protection fault, probably for non-canonical address
> 0xdffffc0000000034: 0000 PREEMPT SMP KASAN NOPTI
> KASAN: null-ptr-deref in range [0x00000000000001a0-0x00000000000001a7]
> CPU: 0 UID: 0 PID: 328415 Comm: repro_36674776 Not tainted 6.12.0-rc1-syzk
> RIP: 0010:x86_pmu_enable_event (arch/x86/events/perf_event.h:1195
> arch/x86/events/core.c:1430)
> RSP: 0018:ffff888118009d60 EFLAGS: 00010012
> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: 0000000000000034 RSI: 0000000000000000 RDI: 00000000000001a0
> RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002
> R13: ffff88811802a440 R14: ffff88811802a240 R15: ffff8881132d8601
> FS: 00007f097dfaa700(0000) GS:ffff888118000000(0000) GS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000200001c0 CR3: 0000000103d56000 CR4: 00000000000006f0
> Call Trace:
> <IRQ>
> amd_pmu_enable_all (arch/x86/events/amd/core.c:760 (discriminator 2))
> x86_pmu_enable (arch/x86/events/core.c:1360)
> event_sched_out (kernel/events/core.c:1191 kernel/events/core.c:1186
> kernel/events/core.c:2346)
> __perf_remove_from_context (kernel/events/core.c:2435)
> event_function (kernel/events/core.c:259)
> remote_function (kernel/events/core.c:92 (discriminator 1)
> kernel/events/core.c:72 (discriminator 1))
> __flush_smp_call_function_queue (./arch/x86/include/asm/jump_label.h:27
> ./include/linux/jump_label.h:207 ./include/trace/events/csd.h:64
> kernel/smp.c:135 kernel/smp.c:540)
> __sysvec_call_function_single (./arch/x86/include/asm/jump_label.h:27
> ./include/linux/jump_label.h:207
> ./arch/x86/include/asm/trace/irq_vectors.h:99 arch/x86/kernel/smp.c:272)
> sysvec_call_function_single (arch/x86/kernel/smp.c:266 (discriminator 47)
> arch/x86/kernel/smp.c:266 (discriminator 47))
> </IRQ>
>
> Reported-by: syzkaller <syzkaller@googlegroups.com>
> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
> ---
Without a Fixes tag it goes into perf/core.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip: perf/core] perf/x86/amd: Check event before enable to avoid GPF
2024-10-08 13:00 [PATCH] [PATCH v3] perf/x86/amd: check event before enable to avoid GPF George Kennedy
2025-10-14 8:37 ` Peter Zijlstra
@ 2025-10-16 9:33 ` tip-bot2 for George Kennedy
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot2 for George Kennedy @ 2025-10-16 9:33 UTC (permalink / raw)
To: linux-tip-commits
Cc: syzkaller, George Kennedy, Peter Zijlstra (Intel), x86, linux-kernel
The following commit has been merged into the perf/core branch of tip:
Commit-ID: 866cf36bfee4fba6a492d2dcc5133f857e3446b0
Gitweb: https://git.kernel.org/tip/866cf36bfee4fba6a492d2dcc5133f857e3446b0
Author: George Kennedy <george.kennedy@oracle.com>
AuthorDate: Tue, 08 Oct 2024 08:00:53 -05:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 16 Oct 2025 11:13:47 +02:00
perf/x86/amd: Check event before enable to avoid GPF
On AMD machines cpuc->events[idx] can become NULL in a subtle race
condition with NMI->throttle->x86_pmu_stop().
Check event for NULL in amd_pmu_enable_all() before enable to avoid a GPF.
This appears to be an AMD only issue.
Syzkaller reported a GPF in amd_pmu_enable_all.
INFO: NMI handler (perf_event_nmi_handler) took too long to run: 13.143
msecs
Oops: general protection fault, probably for non-canonical address
0xdffffc0000000034: 0000 PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000001a0-0x00000000000001a7]
CPU: 0 UID: 0 PID: 328415 Comm: repro_36674776 Not tainted 6.12.0-rc1-syzk
RIP: 0010:x86_pmu_enable_event (arch/x86/events/perf_event.h:1195
arch/x86/events/core.c:1430)
RSP: 0018:ffff888118009d60 EFLAGS: 00010012
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000034 RSI: 0000000000000000 RDI: 00000000000001a0
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002
R13: ffff88811802a440 R14: ffff88811802a240 R15: ffff8881132d8601
FS: 00007f097dfaa700(0000) GS:ffff888118000000(0000) GS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200001c0 CR3: 0000000103d56000 CR4: 00000000000006f0
Call Trace:
<IRQ>
amd_pmu_enable_all (arch/x86/events/amd/core.c:760 (discriminator 2))
x86_pmu_enable (arch/x86/events/core.c:1360)
event_sched_out (kernel/events/core.c:1191 kernel/events/core.c:1186
kernel/events/core.c:2346)
__perf_remove_from_context (kernel/events/core.c:2435)
event_function (kernel/events/core.c:259)
remote_function (kernel/events/core.c:92 (discriminator 1)
kernel/events/core.c:72 (discriminator 1))
__flush_smp_call_function_queue (./arch/x86/include/asm/jump_label.h:27
./include/linux/jump_label.h:207 ./include/trace/events/csd.h:64
kernel/smp.c:135 kernel/smp.c:540)
__sysvec_call_function_single (./arch/x86/include/asm/jump_label.h:27
./include/linux/jump_label.h:207
./arch/x86/include/asm/trace/irq_vectors.h:99 arch/x86/kernel/smp.c:272)
sysvec_call_function_single (arch/x86/kernel/smp.c:266 (discriminator 47)
arch/x86/kernel/smp.c:266 (discriminator 47))
</IRQ>
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/events/amd/core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index b20661b..8868f5f 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -763,7 +763,12 @@ static void amd_pmu_enable_all(int added)
if (!test_bit(idx, cpuc->active_mask))
continue;
- amd_pmu_enable_event(cpuc->events[idx]);
+ /*
+ * FIXME: cpuc->events[idx] can become NULL in a subtle race
+ * condition with NMI->throttle->x86_pmu_stop().
+ */
+ if (cpuc->events[idx])
+ amd_pmu_enable_event(cpuc->events[idx]);
}
}
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-10-08 13:00 [PATCH] [PATCH v3] perf/x86/amd: check event before enable to avoid GPF George Kennedy
2025-10-14 8:37 ` Peter Zijlstra
2025-10-16 9:33 ` [tip: perf/core] perf/x86/amd: Check " tip-bot2 for George Kennedy
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