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authorMarco Elver <elver@google.com>2021-11-09 13:22:32 +0100
committerPeter Zijlstra <peterz@infradead.org>2021-11-23 09:45:37 +0100
commit73743c3b092277febbf69b250ce8ebbca0525aa2 (patch)
tree980fd2820b516fd5fc528c0472a6f3b691d9b912 /kernel/events
parent136057256686de39cc3a07c2e39ef6bc43003ff6 (diff)
perf: Ignore sigtrap for tracepoints destined for other tasks
syzbot reported that the warning in perf_sigtrap() fires, saying that the event's task does not match current: | WARNING: CPU: 0 PID: 9090 at kernel/events/core.c:6446 perf_pending_event+0x40d/0x4b0 kernel/events/core.c:6513 | Modules linked in: | CPU: 0 PID: 9090 Comm: syz-executor.1 Not tainted 5.15.0-syzkaller #0 | Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 | RIP: 0010:perf_sigtrap kernel/events/core.c:6446 [inline] | RIP: 0010:perf_pending_event_disable kernel/events/core.c:6470 [inline] | RIP: 0010:perf_pending_event+0x40d/0x4b0 kernel/events/core.c:6513 | ... | Call Trace: | <IRQ> | irq_work_single+0x106/0x220 kernel/irq_work.c:211 | irq_work_run_list+0x6a/0x90 kernel/irq_work.c:242 | irq_work_run+0x4f/0xd0 kernel/irq_work.c:251 | __sysvec_irq_work+0x95/0x3d0 arch/x86/kernel/irq_work.c:22 | sysvec_irq_work+0x8e/0xc0 arch/x86/kernel/irq_work.c:17 | </IRQ> | <TASK> | asm_sysvec_irq_work+0x12/0x20 arch/x86/include/asm/idtentry.h:664 | RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] | RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:194 | ... | coredump_task_exit kernel/exit.c:371 [inline] | do_exit+0x1865/0x25c0 kernel/exit.c:771 | do_group_exit+0xe7/0x290 kernel/exit.c:929 | get_signal+0x3b0/0x1ce0 kernel/signal.c:2820 | arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 | handle_signal_work kernel/entry/common.c:148 [inline] | exit_to_user_mode_loop kernel/entry/common.c:172 [inline] | exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 | __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] | syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 | do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 | entry_SYSCALL_64_after_hwframe+0x44/0xae On x86 this shouldn't happen, which has arch_irq_work_raise(). The test program sets up a perf event with sigtrap set to fire on the 'sched_wakeup' tracepoint, which fired in ttwu_do_wakeup(). This happened because the 'sched_wakeup' tracepoint also takes a task argument passed on to perf_tp_event(), which is used to deliver the event to that other task. Since we cannot deliver synchronous signals to other tasks, skip an event if perf_tp_event() is targeted at another task and perf_event_attr::sigtrap is set, which will avoid ever entering perf_sigtrap() for such events. Fixes: 97ba62b27867 ("perf: Add support for SIGTRAP on perf events") Reported-by: syzbot+663359e32ce6f1a305ad@syzkaller.appspotmail.com Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/YYpoCOBmC/kJWfmI@elver.google.com
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 523106a506ee..30d94f68c5bd 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9759,6 +9759,9 @@ void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,
continue;
if (event->attr.config != entry->type)
continue;
+ /* Cannot deliver synchronous signal to other task. */
+ if (event->attr.sigtrap)
+ continue;
if (perf_tp_event_match(event, &data, regs))
perf_swevent_event(event, count, &data, regs);
}