perf: fuzzer KASAN slab-out-of-bounds in snb_uncore_imc_event_del

[Vince Weaver]

After turning modversions off I finally managed to get a 4.9-rc kernel to 
boot.

Anyway as per the suggestion at Linux Plumbers I enabled KASAN and on my 
haswell machine it falls over in a few minutes of running the perf_fuzzer.

[  205.740194] ==================================================================
[  205.748005] BUG: KASAN: slab-out-of-bounds in snb_uncore_imc_event_del+0x6c/0xa0 at addr ffff8800caa43768
[  205.758324] Read of size 8 by task perf_fuzzer/6618
[  205.763589] CPU: 0 PID: 6618 Comm: perf_fuzzer Not tainted 4.9.0-rc5 #4
[  205.770721] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014
[  205.778689]  ffff8800c3c479b8 ffffffff816bb796 ffff88011ec00600 ffff8800caa43580
[  205.786759]  ffff8800c3c479e0 ffffffff812fb961 ffff8800c3c47a78 ffff8800caa43580
[  205.794850]  ffff8800caa43580 ffff8800c3c47a68 ffffffff812fbbd8 ffff8800c3c47a28
[  205.802911] Call Trace:
[  205.805559]  [<ffffffff816bb796>] dump_stack+0x63/0x8d
[  205.811135]  [<ffffffff812fb961>] kasan_object_err+0x21/0x70
[  205.817267]  [<ffffffff812fbbd8>] kasan_report_error+0x1d8/0x4c0
[  205.823752]  [<ffffffff81133275>] ? __lock_is_held+0x75/0xc0
[  205.829868]  [<ffffffff81025b12>] ? snb_uncore_imc_read_counter+0x42/0x50
[  205.837198]  [<ffffffff810222e2>] ? uncore_perf_event_update+0xe2/0x160
[  205.844337]  [<ffffffff812fc319>] kasan_report+0x39/0x40
[  205.850085]  [<ffffffff81025e3c>] ? snb_uncore_imc_event_del+0x6c/0xa0
[  205.857114]  [<ffffffff812fa8fe>] __asan_load8+0x5e/0x70
[  205.862874]  [<ffffffff81025e3c>] snb_uncore_imc_event_del+0x6c/0xa0
[  205.869727]  [<ffffffff81241bd2>] event_sched_out.isra.89+0x192/0x690
[  205.876664]  [<ffffffff81242167>] group_sched_out+0x97/0x170
[  205.882760]  [<ffffffff81242810>] __perf_event_disable+0x140/0x1b0
[  205.889395]  [<ffffffff812384e7>] event_function+0x117/0x1f0
[  205.895503]  [<ffffffff812426d0>] ? task_ctx_sched_out+0x60/0x60
[  205.901959]  [<ffffffff812383d0>] ? update_group_times+0x50/0x50
[  205.908425]  [<ffffffff8123b020>] ? perf_cgroup_attach+0xb0/0xb0
[  205.914937]  [<ffffffff8123b096>] remote_function+0x76/0xa0
[  205.920955]  [<ffffffff8118da7c>] generic_exec_single+0xfc/0x170
[  205.927434]  [<ffffffff8123b020>] ? perf_cgroup_attach+0xb0/0xb0
[  205.933883]  [<ffffffff8118dc30>] smp_call_function_single+0x140/0x1b0
[  205.940967]  [<ffffffff8118daf0>] ? generic_exec_single+0x170/0x170
[  205.947776]  [<ffffffff81238e48>] event_function_call+0x268/0x270
[  205.954336]  [<ffffffff812426d0>] ? task_ctx_sched_out+0x60/0x60
[  205.960806]  [<ffffffff81238be0>] ? task_function_call+0xc0/0xc0
[  205.967276]  [<ffffffff812426d0>] ? task_ctx_sched_out+0x60/0x60
[  205.973740]  [<ffffffff81238e79>] ? _perf_event_disable+0x29/0x70
[  205.980300]  [<ffffffff812383d0>] ? update_group_times+0x50/0x50
[  205.986750]  [<ffffffff81238e97>] ? _perf_event_disable+0x47/0x70
[  205.993338]  [<ffffffff8113a4d7>] ? do_raw_spin_unlock+0x97/0x130
[  205.999906]  [<ffffffff81238e50>] ? event_function_call+0x270/0x270
[  206.006674]  [<ffffffff81238ea8>] _perf_event_disable+0x58/0x70
[  206.013069]  [<ffffffff812386a3>] perf_event_for_each_child+0x53/0xd0
[  206.019990]  [<ffffffff81247a51>] perf_event_task_disable+0x61/0xc0
[  206.026759]  [<ffffffff810daee2>] SyS_prctl+0x3f2/0x690
[  206.032409]  [<ffffffff810daaf0>] ? SyS_umask+0x40/0x40
[  206.038059]  [<ffffffff81b8dabb>] entry_SYSCALL_64_fastpath+0x1e/0xb2
[  206.045007] Object at ffff8800caa43580, in cache kmalloc-512 size: 512
[  206.052015] Allocated:
[  206.054565] PID = 1
[  206.056842]  [  206.058367] [<ffffffff8105fcdb>] save_stack_trace+0x1b/0x20
[  206.064410]  [  206.065933] [<ffffffff812facc6>] save_stack+0x46/0xd0
[  206.071416]  [  206.072953] [<ffffffff812faf3d>] kasan_kmalloc+0xad/0xe0
[  206.078683]  [  206.080214] [<ffffffff812f7e3a>] __kmalloc_node+0x4a/0x60
[  206.086061]  [  206.087590] [<ffffffff81020799>] uncore_alloc_box+0x39/0x150
[  206.093685]  [  206.095208] [<ffffffff81020b8f>] uncore_pci_probe+0xff/0x4f0
[  206.101357]  [  206.102879] [<ffffffff8172bc7a>] local_pci_probe+0x7a/0xd0
[  206.108816]  [  206.110347] [<ffffffff8172df6e>] pci_device_probe+0x19e/0x1f0
[  206.116553]  [  206.118073] [<ffffffff818a9a1d>] driver_probe_device+0x25d/0x400
[  206.124566]  [  206.126087] [<ffffffff818a9c9c>] __driver_attach+0xdc/0xe0
[  206.132021]  [  206.133534] [<ffffffff818a653b>] bus_for_each_dev+0xeb/0x150
[  206.139654]  [  206.141184] [<ffffffff818a8f2b>] driver_attach+0x2b/0x30
[  206.146948]  [  206.148493] [<ffffffff818a8900>] bus_add_driver+0x2b0/0x330
[  206.154519]  [  206.156042] [<ffffffff818aa9f3>] driver_register+0xd3/0x190
[  206.164160]  [  206.165688] [<ffffffff8172b2b4>] __pci_register_driver+0xb4/0xc0
[  206.174265]  [  206.175783] [<ffffffff8261553b>] intel_uncore_init+0x2f3/0x388
[  206.184162]  [  206.185672] [<ffffffff81002258>] do_one_initcall+0xa8/0x210
[  206.193721]  [  206.195261] [<ffffffff8260e4c2>] kernel_init_freeable+0x27c/0x312
[  206.203821]  [  206.205349] [<ffffffff81b80b13>] kernel_init+0x13/0x120
[  206.212889]  [  206.214439] [<ffffffff81b8dd35>] ret_from_fork+0x25/0x30
[  206.222067] Freed:
[  206.226172] PID = 0
[  206.230341] (stack is not available)
[  206.236044] Memory state around the buggy address:
[  206.243157]  ffff8800caa43600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  206.252788]  ffff8800caa43680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  206.262437] >ffff8800caa43700: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
[  206.272071]                                                           ^
[  206.281005]  ffff8800caa43780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  206.290640]  ffff8800caa43800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  206.300302] 
==================================================================