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raise(-1) succeeds for programs linked against libpthread
From: |
Ludovic Courtès |
Subject: |
raise(-1) succeeds for programs linked against libpthread |
Date: |
Tue, 13 Oct 2020 15:41:37 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) |
Hi!
(Cc: bug-hurd.)
Jan Nieuwenhuizen <janneke@gnu.org> skribis:
>>> #include <signal.h>
>>>
>>> int
>>> main (void)
>>> {
>>> if (!raise (-1))
>>> return 1;
>>>
>>> return 0;
>>> }
>>
>> I don’t know if it’s relevant here, but you should always use ‘-pthread’
>> both at compile time and link time:
>>
>> gcc raise.c -pthread
>>
>> That typically defines a few macros that may or may not have an effect
>> on the code at hand.
>
> Ah...right. Makes no difference, though:
>
> root@childhurd ~# guix environment --bootstrap --ad-hoc gcc-toolchain@7
> root@childhurd ~ [env]# gcc raise.c
> root@childhurd ~ [env]# ./a.out
> root@childhurd ~ [env]# echo $?
> 0
> root@childhurd ~ [env]# gcc raise.c -pthread
> root@childhurd ~ [env]# ./a.out
> User defined signal 2
Interesting! In the second case, we’re using ‘__pthread_kill’ from
‘pt-kill.c’ (instead of ‘kill’).
The expected behavior is that ‘raise’ should return non-zero and EINVAL.
‘pthread_kill’ passes the signal number to ‘_hurd_raise_signal’, which
assumes it is valid:
--8<---------------cut here---------------start------------->8---
int
_hurd_raise_signal (struct hurd_sigstate *ss,
int signo, const struct hurd_signal_detail *detail)
{
if (ss == NULL)
{
ss = _hurd_self_sigstate ();
__spin_lock (&ss->lock);
}
/* Mark SIGNO as pending to be delivered. */
__sigaddset (&ss->pending, signo);
ss->pending_data[signo] = *detail;
--8<---------------cut here---------------end--------------->8---
I suppose that before calling ‘sigaddset’, it should check whether SIGNO
is within bounds, along the lines of:
if (signo < 2 || signo >= _NSIG)
return EINVAL;
Does that make sense?
Thanks,
Ludo’.