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signal: In get_signal test for signal_group_exit every time through the loop

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Recently while investigating a problem with rr and signals I noticed
that siglock is dropped in ptrace_signal and get_signal does not jump
to relock.

Looking farther to see if the problem is anywhere else I see that
do_signal_stop also returns if signal_group_exit is true.  I believe
that test can now never be true, but it is a bit hard to trace
through and be certain.

Testing signal_group_exit is not expensive, so move the test for
signal_group_exit into the for loop inside of get_signal to ensure
the test is never skipped improperly.

This has been a potential problem since I added the test for
signal_group_exit was added.

Fixes: 35634ffa1751 ("signal: Always notice exiting tasks")
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/875yssekcd.fsf_-_@email.froward.int.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2021-11-15 11:55:57 -06:00
parent fa55b7dcdc
commit e7f7c99ba9
1 changed files with 10 additions and 10 deletions
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20
kernel/signal.c
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@ -2662,19 +2662,19 @@ relock:
goto relock;
}
/* Has this task already been marked for death? */
if (signal_group_exit(signal)) {
ksig->info.si_signo = signr = SIGKILL;
sigdelset(&current->pending.signal, SIGKILL);
trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
&sighand->action[SIGKILL - 1]);
recalc_sigpending();
goto fatal;
}
for (;;) {
struct k_sigaction *ka;
/* Has this task already been marked for death? */
if (signal_group_exit(signal)) {
ksig->info.si_signo = signr = SIGKILL;
sigdelset(&current->pending.signal, SIGKILL);
trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
&sighand->action[SIGKILL - 1]);
recalc_sigpending();
goto fatal;
}
if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
do_signal_stop(0))
goto relock;