Re: perf: fuzzer KASAN unwind_get_return_address

[Peter Zijlstra]

On Tue, Nov 15, 2016 at 02:57:48PM -0600, Josh Poimboeuf wrote:
> Would you mind posting a disassembly of unwind_get_return_address()?

$ objdump -D ivb-dbg/vmlinux | awk '/<[^>]*>:/ { p=0; } /<unwind_get_return_address>:/ { p=1; } { if (p) print $0; }'

ffffffff811afd10 <unwind_get_return_address>:
ffffffff811afd10:       e8 eb cc f4 01          callq  ffffffff830fca00 <__fentry__>
ffffffff811afd15:       48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
ffffffff811afd1c:       fc ff df 
ffffffff811afd1f:       48 89 fa                mov    %rdi,%rdx
ffffffff811afd22:       53                      push   %rbx
ffffffff811afd23:       48 89 fb                mov    %rdi,%rbx
ffffffff811afd26:       48 c1 ea 03             shr    $0x3,%rdx
ffffffff811afd2a:       48 83 ec 18             sub    $0x18,%rsp
ffffffff811afd2e:       0f b6 14 02             movzbl (%rdx,%rax,1),%edx
ffffffff811afd32:       48 89 f8                mov    %rdi,%rax
ffffffff811afd35:       83 e0 07                and    $0x7,%eax
ffffffff811afd38:       83 c0 03                add    $0x3,%eax
ffffffff811afd3b:       38 d0                   cmp    %dl,%al
ffffffff811afd3d:       7c 04                   jl     ffffffff811afd43 <unwind_get_return_address+0x33>
ffffffff811afd3f:       84 d2                   test   %dl,%dl
ffffffff811afd41:       75 75                   jne    ffffffff811afdb8 <unwind_get_return_address+0xa8>
ffffffff811afd43:       8b 03                   mov    (%rbx),%eax
ffffffff811afd45:       85 c0                   test   %eax,%eax
ffffffff811afd47:       75 08                   jne    ffffffff811afd51 <unwind_get_return_address+0x41>
ffffffff811afd49:       48 83 c4 18             add    $0x18,%rsp
ffffffff811afd4d:       31 c0                   xor    %eax,%eax
ffffffff811afd4f:       5b                      pop    %rbx
ffffffff811afd50:       c3                      retq   
ffffffff811afd51:       48 8d 7b 38             lea    0x38(%rbx),%rdi
ffffffff811afd55:       48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
ffffffff811afd5c:       fc ff df 
ffffffff811afd5f:       48 89 fa                mov    %rdi,%rdx
ffffffff811afd62:       48 c1 ea 03             shr    $0x3,%rdx
ffffffff811afd66:       80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1)
ffffffff811afd6a:       75 53                   jne    ffffffff811afdbf <unwind_get_return_address+0xaf>
ffffffff811afd6c:       48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
ffffffff811afd73:       fc ff df 
ffffffff811afd76:       48 8b 4b 38             mov    0x38(%rbx),%rcx
ffffffff811afd7a:       48 89 ca                mov    %rcx,%rdx
ffffffff811afd7d:       48 c1 ea 03             shr    $0x3,%rdx
ffffffff811afd81:       80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1)
ffffffff811afd85:       75 3f                   jne    ffffffff811afdc6 <unwind_get_return_address+0xb6>
ffffffff811afd87:       48 8d 7b 28             lea    0x28(%rbx),%rdi
ffffffff811afd8b:       48 8b 11                mov    (%rcx),%rdx
ffffffff811afd8e:       48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
ffffffff811afd95:       fc ff df 
ffffffff811afd98:       48 8d 73 30             lea    0x30(%rbx),%rsi
ffffffff811afd9c:       49 89 f8                mov    %rdi,%r8
ffffffff811afd9f:       49 c1 e8 03             shr    $0x3,%r8
ffffffff811afda3:       41 80 3c 00 00          cmpb   $0x0,(%r8,%rax,1)
ffffffff811afda8:       75 2e                   jne    ffffffff811afdd8 <unwind_get_return_address+0xc8>
ffffffff811afdaa:       48 8b 7b 28             mov    0x28(%rbx),%rdi
ffffffff811afdae:       48 83 c4 18             add    $0x18,%rsp
ffffffff811afdb2:       5b                      pop    %rbx
ffffffff811afdb3:       e9 08 98 2a 00          jmpq   ffffffff814595c0 <ftrace_graph_ret_addr>
ffffffff811afdb8:       e8 53 7d 42 00          callq  ffffffff815d7b10 <__asan_report_load4_noabort>
ffffffff811afdbd:       eb 84                   jmp    ffffffff811afd43 <unwind_get_return_address+0x33>
ffffffff811afdbf:       e8 9c 7d 42 00          callq  ffffffff815d7b60 <__asan_report_load8_noabort>
ffffffff811afdc4:       eb a6                   jmp    ffffffff811afd6c <unwind_get_return_address+0x5c>
ffffffff811afdc6:       48 89 cf                mov    %rcx,%rdi
ffffffff811afdc9:       48 89 0c 24             mov    %rcx,(%rsp)
ffffffff811afdcd:       e8 8e 7d 42 00          callq  ffffffff815d7b60 <__asan_report_load8_noabort>
ffffffff811afdd2:       48 8b 0c 24             mov    (%rsp),%rcx
ffffffff811afdd6:       eb af                   jmp    ffffffff811afd87 <unwind_get_return_address+0x77>
ffffffff811afdd8:       48 89 74 24 10          mov    %rsi,0x10(%rsp)
ffffffff811afddd:       48 89 54 24 08          mov    %rdx,0x8(%rsp)
ffffffff811afde2:       48 89 0c 24             mov    %rcx,(%rsp)
ffffffff811afde6:       e8 75 7d 42 00          callq  ffffffff815d7b60 <__asan_report_load8_noabort>
ffffffff811afdeb:       48 8b 74 24 10          mov    0x10(%rsp),%rsi
ffffffff811afdf0:       48 8b 54 24 08          mov    0x8(%rsp),%rdx
ffffffff811afdf5:       48 8b 0c 24             mov    (%rsp),%rcx
ffffffff811afdf9:       eb af                   jmp    ffffffff811afdaa <unwind_get_return_address+0x9a>
ffffffff811afdfb:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)

> Any idea how recreatable it is?  (In particular I'd be interested in
> seeing this dump with the latest unwinder improvements in the -tip tree,
> which dump the pt_regs associated with an interrupt.)

Fairly reproducable it seems, doesn't seem to include pt_regs dumps
though :/

tip/master as of this morning.

3==================================================================
3BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0x1ba/0x1f0 at addr ffff88042fc87be0
3Read of size 8 by task swapper/28/0
0page:ffffea0010bf21c0 count:1 mapcount:0 mapping:          (null) index:0x0c
0flags: 0x2ffff8000000400(reserved)
1page dumped because: kasan: bad access detected
dCPU: 28 PID: 0 Comm: swapper/28 Not tainted 4.9.0-rc5-00530-gd8866fc-dirty #2
dHardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
dCall Trace:
d <NMI>
d ? dump_stack+0x5e/0x89
d ? kasan_report_error+0x4a5/0x4d0
d ? __asan_report_load8_noabort+0x45/0x50
d ? __kernel_text_address+0x20/0xa0
d ? unwind_next_frame+0x1ba/0x1f0
d ? unwind_next_frame+0x1ba/0x1f0
d ? perf_callchain_kernel+0x33c/0x540
d ? arch_perf_update_userpage+0x340/0x340
d ? get_perf_callchain+0x24d/0x610
d ? put_callchain_buffers+0x50/0x50
d ? number+0x653/0x830
d ? perf_callchain+0x126/0x190
d ? perf_prepare_sample+0x720/0x1010
d ? perf_event_output_forward+0x81/0xf0
d ? perf_prepare_sample+0x1010/0x1010
d ? pointer+0x880/0x880
d ? perf_event_update_userpage+0x16/0x730
d ? __perf_event_overflow+0x1a0/0x510
d ? intel_pmu_handle_irq+0x34b/0xa90
d ? intel_pmu_save_and_restart+0xd0/0xd0
d ? acpi_os_read_memory+0x205/0x23c
d ? format_decode+0xc5/0x7a0
d ? vunmap_page_range+0x26a/0x400
d ? ghes_copy_tofrom_phys+0x141/0x270
d ? ghes_read_estatus+0x112/0x5a0
d ? ghes_copy_tofrom_phys+0x270/0x270
d ? early_printk+0xa4/0xd0
d ? devkmsg_sysctl_set_loglvl+0x160/0x160
d ? perf_event_nmi_handler+0x28/0x40
d ? nmi_handle+0xa1/0x250
d ? default_do_nmi+0x61/0x170
d ? do_nmi+0x191/0x200
d ? end_repeat_nmi+0x1a/0x1e
d ? format_decode+0xc5/0x7a0
d ? format_decode+0xc5/0x7a0
d ? format_decode+0xc5/0x7a0
d <EOE>
d <IRQ>
d ? vsnprintf+0xfc/0x15e0
d ? pointer+0x880/0x880
d ? x86_pmu_enable_all+0x1c0/0x1c0
d ? vscnprintf+0x9/0x30
d ? early_vprintk+0xb0/0x130
d ? trace_raw_output_console+0x160/0x160
d ? memcpy+0x34/0x50
d ? x86_pmu_commit_txn+0x180/0x260
d ? events_sysfs_show+0xb0/0xb0
d ? save_stack+0x33/0xb0
d ? hrtimer_init+0x120/0x120
d ? timerqueue_del+0x62/0x140
d ? perf_event_update_userpage+0x16/0x730
d ? perf_event_update_userpage+0x16/0x730
d ? x86_perf_event_set_period+0x239/0x450
d ? perf_event_update_userpage+0x16/0x730
d ? x86_pmu_enable+0x5f7/0xaa0
d ? printk+0xb6/0xef
d ? printk_emit+0xa0/0xa0
d ? _raw_spin_unlock_irqrestore+0x42/0x70
d ? ___ratelimit+0x1e4/0x3f0
d ? irq_work_run_list+0xa1/0xf0
d ? irq_work_run+0x14/0x40
d ? smp_call_function_single_interrupt+0x60/0x80
d ? call_function_single_interrupt+0x89/0x90
d <EOI>
d ? cpuidle_enter_state+0x113/0x780
d ? cpuidle_enter_state+0x10e/0x780
d ? cpu_load_update_nohz_stop+0x155/0x1b0
d ? cpu_startup_entry+0x19a/0x2c0
d ? start_cpu+0x5/0x14
3Memory state around the buggy address:
3 ffff88042fc87a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
3 ffff88042fc87b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
3>ffff88042fc87b80: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
3                                                       ^
3 ffff88042fc87c00: 00 f4 f4 f4 f3 f3 f3 f3 00 00 00 00 00 00 00 00
3 ffff88042fc87c80: 00 f1 f1 f1 f1 00 00 00 00 00 00 00 00 00 00 00
3==================================================================


3==================================================================
3BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0x1ba/0x1f0 at addr ffff880424a97878
3Read of size 8 by task perf_fuzzer/3451
0page:ffffea001092a5c0 count:0 mapcount:0 mapping:          (null) index:0x0c
0flags: 0x2ffff8000000000()
1page dumped because: kasan: bad access detected
dCPU: 28 PID: 3451 Comm: perf_fuzzer Not tainted 4.9.0-rc5-00530-gd8866fc-dirty #2
dHardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
dCall Trace:
d ? dump_stack+0x5e/0x89
d ? kasan_report_error+0x4a5/0x4d0
d ? __asan_report_load8_noabort+0x45/0x50
d ? __kernel_text_address+0x20/0xa0
d ? unwind_next_frame+0x1ba/0x1f0
d ? unwind_next_frame+0x1ba/0x1f0
d ? perf_callchain_kernel+0x33c/0x540
d ? arch_perf_update_userpage+0x340/0x340
d ? get_perf_callchain+0x24d/0x610
d ? put_callchain_buffers+0x50/0x50
d ? ipv6_flowlabel_opt+0x1111/0x17d0
d ? perf_log_itrace_start+0x3a0/0x3a0
d ? cpumask_next_and+0x5a/0xa0
d ? ktime_get_raw_fast_ns+0xd3/0x1e0
d ? perf_callchain+0x126/0x190
d ? perf_prepare_sample+0x720/0x1010
d ? perf_event_output_forward+0x81/0xf0
d ? perf_prepare_sample+0x1010/0x1010
d ? perf_event_update_userpage+0x16/0x730
d ? kasan_unpoison_shadow+0x31/0x40
d ? get_page_from_freelist+0x52e/0x2310
d ? perf_output_begin+0x3a1/0x9b0
d ? cpu_clock_event_add+0x17/0x20
d ? __perf_event_overflow+0x1a0/0x510
d ? perf_swevent_overflow+0x156/0x1f0
d ? perf_tp_event+0x3e8/0x5c0
d ? perf_output_begin_backward+0x960/0x960
d ? perf_tp_event_match.isra.85.part.86+0x140/0x140
d ? __mark_inode_dirty+0x459/0xa50
d ? legitimize_path.isra.28+0x6b/0x150
d ? unlazy_walk+0x456/0x790
d ? memset+0x1f/0x40
d ? perf_trace_writeback_dirty_inode_template+0x3af/0x610
d ? save_stack+0x33/0xb0
d ? inode_congested+0x450/0x450
d ? dput+0x1de/0x530
d ? walk_component+0x2cc/0xdc0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? pick_link+0xbe0/0xbe0
d ? inode_congested+0x450/0x450
d ? __mark_inode_dirty+0x459/0xa50
d ? proc_sys_setattr+0x84/0xb0
d ? notify_change+0x4d6/0xc40
d ? security_inode_need_killpriv+0x58/0x80
d ? do_truncate+0xd7/0x160
d ? file_open_root+0x1a0/0x1a0
d ? path_openat+0x97f/0x3b30
d ? vfs_rename+0x14a0/0x14a0
d ? getname_flags+0xba/0x500
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? do_filp_open+0x175/0x230
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? may_open_dev+0xc0/0xc0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? save_stack+0x33/0xb0
d ? do_sys_open+0x16d/0x310
d ? SyS_write+0xab/0x160
d ? filp_open+0x50/0x50
d ? task_stopped_code+0xf0/0xf0
d ? trace_hardirqs_on_thunk+0x1a/0x1c
d ? entry_SYSCALL_64_fastpath+0x18/0xa8
3Memory state around the buggy address:
3 ffff880424a97700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
3 ffff880424a97780: 00 00 00 00 00 00 00 00 f3 f3 f3 f3 f3 f3 f3 f3
3>ffff880424a97800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1
3                                                                ^
3 ffff880424a97880: f1 f1 f1 04 f4 f4 f4 f2 f2 f2 f2 00 f4 f4 f4 f3
3 ffff880424a97900: f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00
3==================================================================