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| author | Eric W. Biederman <ebiederm@xmission.com> | 2019-02-11 23:27:42 -0600 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2019-02-13 08:31:41 -0600 |
| commit | cf43a757fd49442bc38f76088b70c2299eed2c2f (patch) | |
| tree | d185fedd4ce0e6d8e9cde9d7bd538de030a3c9da /kernel/signal.c | |
| parent | 7146db3317c67b517258cb5e1b08af387da0618b (diff) | |
| download | lwn-cf43a757fd49442bc38f76088b70c2299eed2c2f.tar.gz lwn-cf43a757fd49442bc38f76088b70c2299eed2c2f.zip | |
signal: Restore the stop PTRACE_EVENT_EXIT
In the middle of do_exit() there is there is a call
"ptrace_event(PTRACE_EVENT_EXIT, code);" That call places the process
in TACKED_TRACED aka "(TASK_WAKEKILL | __TASK_TRACED)" and waits for
for the debugger to release the task or SIGKILL to be delivered.
Skipping past dequeue_signal when we know a fatal signal has already
been delivered resulted in SIGKILL remaining pending and
TIF_SIGPENDING remaining set. This in turn caused the
scheduler to not sleep in PTACE_EVENT_EXIT as it figured
a fatal signal was pending. This also caused ptrace_freeze_traced
in ptrace_check_attach to fail because it left a per thread
SIGKILL pending which is what fatal_signal_pending tests for.
This difference in signal state caused strace to report
strace: Exit of unknown pid NNNNN ignored
Therefore update the signal handling state like dequeue_signal
would when removing a per thread SIGKILL, by removing SIGKILL
from the per thread signal mask and clearing TIF_SIGPENDING.
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Ivan Delalande <colona@arista.com>
Cc: stable@vger.kernel.org
Fixes: 35634ffa1751 ("signal: Always notice exiting tasks")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 99fa8ff06fd9..57b7771e20d7 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2436,9 +2436,12 @@ relock: } /* Has this task already been marked for death? */ - ksig->info.si_signo = signr = SIGKILL; - if (signal_group_exit(signal)) + if (signal_group_exit(signal)) { + ksig->info.si_signo = signr = SIGKILL; + sigdelset(¤t->pending.signal, SIGKILL); + recalc_sigpending(); goto fatal; + } for (;;) { struct k_sigaction *ka; |