perf: perf_fuzzer triggers GPF in perf_prepare_sample

[Vince Weaver]

Hello,

I was able to trigger another oops with the perf_fuzzer with current git.

This is 4.20-rc5 after the fix for the very similar oops I previously 
reported got committed.

It seems to be pointing to the same location in the source as 
before, I guess maybe triggered a different way?

Unfortunately this crash is not easily reproducible like the last one was.

kernel/events/core.c:6393

if (sample_type & PERF_SAMPLE_CALLCHAIN) {
                int size = 1;

                if (!(sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
                        data->callchain = perf_callchain(event, regs);

>>>>>>>>>       size += data->callchain->nr;

                header->size += size * sizeof(u64);
        }


Vince

[45050.698745] general protection fault: 0000 [#1] SMP PTI
[45050.698745] CPU: 5 PID: 13475 Comm: perf_fuzzer Tainted: G        W         4.20.0-rc5 #124
[45050.698746] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014
[45050.698746] RIP: 0010:perf_prepare_sample+0x82/0x4a0
[45050.698746] Code: 06 4c 89 ea 4c 89 e6 e8 3c 54 ff ff 40 f6 c5 01 0f 85 28 01 00 00 40 f6 c5 20 74 1c 48 85 ed 0f 89 04 01 00 00 49 8b 44 24 70 <48> 8b 00 8d 04 c5 08 00 00 00 66 01 43 06 f7 c5 00 04 00 00 74 41
[45050.698747] RSP: 0000:ffffc900206bfb00 EFLAGS: 00010082
[45050.698747] RAX: dead000000000200 RBX: ffffc900206bfb58 RCX: 000000000000001f
[45050.698747] RDX: 0000000000000000 RSI: 0000000025bbf56f RDI: 0000000000000000
[45050.698748] RBP: 8000000000000275 R08: 0000000000000002 R09: 00000000000215c0
[45050.698748] R10: 00008b25b2e2f5c8 R11: 0000000000000000 R12: ffffc900206bfc40
[45050.698748] R13: ffff8880cf6d7800 R14: ffffc900206bfb98 R15: ffff88811ab4f420
[45050.698748] FS:  00007fab66133500(0000) GS:ffff88811ab40000(0000) knlGS:0000000000000000
[45050.698749] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[45050.698749] CR2: 00007fab66133480 CR3: 00000000811aa004 CR4: 00000000001607e0
[45050.698749] DR0: 0000000000000000 DR1: 000000008e8e8000 DR2: 0000000000000000
[45050.698749] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
[45050.698750] Call Trace:
[45050.698750]  intel_pmu_drain_bts_buffer+0x151/0x220
[45050.698750]  ? mem_cgroup_commit_charge+0x7a/0x510
[45050.698750]  ? wp_page_copy+0x39e/0x650
[45050.698750]  ? reuse_swap_page+0x129/0x340
[45050.698751]  ? _raw_spin_unlock+0xa/0x10
[45050.698751]  ? do_wp_page+0x30f/0x4d0
[45050.698751]  ? finish_mkwrite_fault+0x140/0x140
[45050.698751]  ? __handle_mm_fault+0xb22/0x12c0
[45050.698751]  intel_pmu_handle_irq+0x6d/0x160
[45050.698752]  perf_event_nmi_handler+0x2d/0x50
[45050.698752]  nmi_handle+0x63/0x110
[45050.698752]  default_do_nmi+0x4e/0x100
[45050.698752]  do_nmi+0x112/0x170
[45050.698752]  nmi+0x8b/0xd4
[45050.698753] RIP: 0033:0x558a6a6366c3
[45050.698753] Code: 01 d0 48 c1 e0 06 48 89 c2 48 8d 05 cf 93 23 00 48 8b 04 02 48 85 c0 74 11 8b 45 f8 3b 45 f4 75 05 8b 45 fc eb 16 83 45 f8 01 <83> 45 fc 01 81 7d fc 9f 86 01 00 7e 96 b8 ff ff ff ff c9 c3 55 48
[45050.698753] RSP: 002b:00007ffc9f521660 EFLAGS: 00000246
[45050.698754] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000030
[45050.698754] RDX: 000000000000e740 RSI: 00007ffc9f521634 RDI: 00007fab6612c740
[45050.698754] RBP: 00007ffc9f521670 R08: 00007fab6612c1f0 R09: 00007fab6612c240
[45050.698754] R10: 00007fab661337d0 R11: 0000000000000246 R12: 0000558a6a6364c0
[45050.698755] R13: 00007ffc9f523ad0 R14: 0000000000000000 R15: 0000000000000000
[45050.698755] Modules linked in: intel_rapl x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec_hdmi snd_hda_intel coretemp tpm_tis snd_hda_codec snd_hda_core kvm_intel tpm_tis_core i915 snd_hwdep kvm tpm snd_pcm rng_core wmi_bmof mei_me sg iosf_mbi irqbypass drm_kms_helper evdev crct10dif_pclmul drm mei iTCO_wdt i2c_algo_bit iTCO_vendor_support snd_timer pcc_cpufreq crc32_pclmul ghash_clmulni_intel aesni_intel snd video aes_x86_64 crypto_simd cryptd glue_helper soundcore pcspkr wmi button binfmt_misc ip_tables x_tables autofs4 sr_mod sd_mod cdrom ahci libahci ehci_pci xhci_pci libata xhci_hcd ehci_hcd lpc_ich mfd_core crc32c_intel scsi_mod e1000e i2c_i801 usbcore usb_common fan thermal[45051.027024] ---[ end trace 9565944010fbdf23 ]---
[45051.027024] RIP: 0010:perf_prepare_sample+0x82/0x4a0
[45051.027025] Code: 06 4c 89 ea 4c 89 e6 e8 3c 54 ff ff 40 f6 c5 01 0f 85 28 01 00 00 40 f6 c5 20 74 1c 48 85 ed 0f 89 04 01 00 00 49 8b 44 24 70 <48> 8b 00 8d 04 c5 08 00 00 00 66 01 43 06 f7 c5 00 04 00 00 74 41
[45051.027025] RSP: 0000:ffffc900206bfb00 EFLAGS: 00010082
[45051.027025] RAX: dead000000000200 RBX: ffffc900206bfb58 RCX: 000000000000001f
[45051.027025] RDX: 0000000000000000 RSI: 0000000025bbf56f RDI: 0000000000000000
[45051.027026] RBP: 8000000000000275 R08: 0000000000000002 R09: 00000000000215c0
[45051.027026] R10: 00008b25b2e2f5c8 R11: 0000000000000000 R12: ffffc900206bfc40
[45051.027026] R13: ffff8880cf6d7800 R14: ffffc900206bfb98 R15: ffff88811ab4f420
[45051.027027] FS:  00007fab66133500(0000) GS:ffff88811ab40000(0000) knlGS:0000000000000000
[45051.027027] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[45051.027027] CR2: 00007fab66133480 CR3: 00000000811aa004 CR4: 00000000001607e0
[45051.027027] DR0: 0000000000000000 DR1: 000000008e8e8000 DR2: 0000000000000000
[45051.027027] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
[45051.027028] Kernel panic - not syncing: Fatal exception in interrupt
[45051.027051] Kernel Offset: disabled
[45051.149441] ---[ end Kernel panic - not syncing: Fatal exception in interrupt]---