Re: [PATCH 4.19.y 00/13] fix double-free bug causing by destroy_hist_field(data->onmax.var, 0)

Greg KH
2024-05-23T12:09:54Z

On Thu, May 09, 2024 at 10:29:18AM +0800, George Guo wrote:
> Hi,
>
> There are 3 points about this bug:
>
> 1)
> The onmax_destroy() destroyed the onmax var, casusing a double-free error
> flagged by KASAN.
>
> This is tested via "./ftracetest test.d/trigger/inter-event/trigger-onmatch-onmax-action-hist.tc".
>
> ==================================================================
> BUG: KASAN: use-after-free in destroy_hist_field+0x1c2/0x200
> Read of size 8 at addr ffff88800a4ad100 by task ftracetest/4731
>
> CPU: 0 PID: 4731 Comm: ftracetest Kdump: loaded Tainted: GE 4.19.90-89 #77
> Source Version: Unknown
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0
> Call Trace:
> dump_stack+0xcb/0x10b
> print_address_description.cold+0x54/0x249
> kasan_report_error.cold+0x63/0xab
> ? destroy_hist_field+0x1c2/0x200
> ? hist_trigger_elt_data_alloc+0x5a0/0x5a0
> __asan_report_load8_noabort+0x8d/0xa0
> ? destroy_hist_field+0x1c2/0x200
> destroy_hist_field+0x1c2/0x200
> onmax_destroy+0x72/0x1e0
> ? hist_trigger_elt_data_alloc+0x5a0/0x5a0
> destroy_hist_data+0x236/0xa40
> event_hist_trigger_free+0x212/0x2f0
> ? update_cond_flag+0x128/0x170
> ? event_hist_trigger_func+0x2880/0x2880
> hist_unregister_trigger+0x2f2/0x4f0
> event_hist_trigger_func+0x168c/0x2880
> ? tracing_map_cmp_u64+0xa0/0xa0
> ? onmatch_create.constprop.0+0xf50/0xf50
> ? __mutex_lock_slowpath+0x10/0x10
> event_trigger_write+0x2f4/0x490
> ? trigger_start+0x180/0x180
> ? __fget_light+0x369/0x5d0
> ? count_memcg_event_mm+0x104/0x2b0
> ? trigger_start+0x180/0x180
> __vfs_write+0x81/0x100
> vfs_write+0x1e1/0x540
> ksys_write+0x12a/0x290
> ? __ia32_sys_read+0xb0/0xb0
> ? __close_fd+0x1d3/0x280
> do_syscall_64+0xe3/0x2d0
> entry_SYSCALL_64_after_hwframe+0x5c/0xc1
> RIP: 0033:0x7fd7f4c44e04
> Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00
> 48 8d 05 39 34 0c 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00
> f0 ff ff 77 54 f3 c3 66 90 41 54 55 49 89 d4 53 48 89 f5
> RSP: 002b:00007fff10370df8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 000000000000010f RCX: 00007fd7f4c44e04
> RDX: 000000000000010f RSI: 000055fa765df650 RDI: 0000000000000001
> RBP: 000055fa765df650 R08: 000000000000000a R09: 0000000000000000
> R10: 000000000000000a R11: 0000000000000246 R12: 00007fd7f4d035c0
> R13: 000000000000010f R14: 00007fd7f4d037c0 R15: 000000000000010f
> ==================================================================
>
> 2)
> So remove the onmax_destroy() destroy_hist_field() call for that var.
>
> just like this demo patch:
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 7dcb96305e56..58b8a2575b8c 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -3489,7 +3488,6 @@ static void onmax_destroy(struct action_data *data)
> unsigned int i;
>
> destroy_hist_field(data->onmax.max_var, 0);
> - destroy_hist_field(data->onmax.var, 0);
>
> kfree(data->onmax.var_str);
> kfree(data->onmax.fn_name);
> --
>
> 3)
> And I found it has been fixed by upstream commit ff9d31d0d466.
> So I am backporting these patches to linux-4.19.y.
>
>
> Masami Hiramatsu (4):
> tracing: Simplify creation and deletion of synthetic events
> tracing: Add unified dynamic event framework
> tracing: Use dyn_event framework for synthetic events
> tracing: Remove unneeded synth_event_mutex
>
> Steven Rostedt (VMware) (5):
> tracing: Consolidate trace_add/remove_event_call back to the nolock
> functions
> string.h: Add str_has_prefix() helper function
> tracing: Use str_has_prefix() helper for histogram code
> tracing: Use str_has_prefix() instead of using fixed sizes
> tracing: Have the historgram use the result of str_has_prefix() for
> len of prefix
>
> Tom Zanussi (4):
> tracing: Refactor hist trigger action code
> tracing: Split up onmatch action data
> tracing: Generalize hist trigger onmax and save action
> tracing: Remove unnecessary var_ref destroy in track_data_destroy()
>
> include/linux/string.h | 20 +
> include/linux/trace_events.h | 2 -
> kernel/trace/Kconfig | 4 +
> kernel/trace/Makefile | 1 +
> kernel/trace/trace.c | 26 +-
> kernel/trace/trace_dynevent.c | 210 ++++++
> kernel/trace/trace_dynevent.h | 119 ++++
> kernel/trace/trace_events.c | 32 +-
> kernel/trace/trace_events_hist.c | 1048 ++++++++++++++++++------------
> kernel/trace/trace_probe.c | 2 +-
> kernel/trace/trace_stack.c | 2 +-
> 11 files changed, 1008 insertions(+), 458 deletions(-)
> create mode 100644 kernel/trace/trace_dynevent.c
> create mode 100644 kernel/trace/trace_dynevent.h
>
> --
> 2.34.1
>
>

Thanks for the backports, all now queued up.

greg k-h