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linux/arch/x86/events
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George Kennedy 43c2e5c2ac perf/x86/amd: Check event before enable to avoid GPF 
[ Upstream commit 866cf36bfe ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-01-02 12:56:38 +01:00
..
amd perf/x86/amd: Check event before enable to avoid GPF 2026-01-02 12:56:38 +01:00
intel perf/x86/intel: Fix NULL event dereference crash in handle_pmi_common() 2025-12-18 14:03:41 +01:00
zhaoxin Core x86 updates for v6.16: 2025-05-26 16:04:17 -07:00
core.c perf/x86: Fix NULL event access and potential PEBS record loss 2025-12-18 14:02:52 +01:00
Kconfig perf/x86/Kconfig: Fix indentation in the Kconfig file 2022-05-25 15:54:26 +02:00
Makefile perf/x86: Move branch classifier 2022-08-27 00:05:44 +02:00
msr.c x86/msr: Add explicit includes of <asm/msr.h> 2025-05-02 10:23:47 +02:00
perf_event.h Core x86 updates for v6.16: 2025-05-26 16:04:17 -07:00
perf_event_flags.h perf: Extend the bit width of the arch-specific flag 2025-04-08 20:55:49 +02:00
probe.c x86/msr: Add explicit includes of <asm/msr.h> 2025-05-02 10:23:47 +02:00
probe.h perf/x86/rapl: Add msr mask support 2021-02-10 14:44:54 +01:00
rapl.c x86/msr: Add explicit includes of <asm/msr.h> 2025-05-02 10:23:47 +02:00
utils.c x86/msr: Add explicit includes of <asm/msr.h> 2025-05-02 10:23:47 +02:00