From: George Kennedy <george.kennedy@oracle.com>
To: ravi.bangoria@amd.com
Cc: george.kennedy@oracle.com, harshit.m.mogalapalli@oracle.com,
peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
namhyung@kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@kernel.org,
irogers@google.com, adrian.hunter@intel.com,
kan.liang@linux.intel.com, tglx@linutronix.de, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
dongli.zhang@oracle.com
Subject: [PATCH] [PATCH v2] perf/x86/amd: check event before enable to avoid GPF
Date: Mon, 30 Sep 2024 14:52:27 -0500 [thread overview]
Message-ID: <1727725947-18058-1-git-send-email-george.kennedy@oracle.com> (raw)
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>
---
Ravi requested patch resend with the following:
/*
* FIXME: cpuc->events[idx] can become NULL in a subtle race
* condition with NMI->throttle->x86_pmu_stop().
*/
arch/x86/events/amd/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 920e3a640cad..3a8b8db878f6 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -762,7 +762,8 @@ static void amd_pmu_enable_all(int added)
if (!test_bit(idx, cpuc->active_mask))
continue;
- amd_pmu_enable_event(cpuc->events[idx]);
+ if (cpuc->events[idx])
+ amd_pmu_enable_event(cpuc->events[idx]);
}
}
--
2.39.3
next reply other threads:[~2024-09-30 19:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-30 19:52 George Kennedy [this message]
2024-10-07 6:43 ` Ravi Bangoria
2025-10-09 7:12 ` Peter Zijlstra
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