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
