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nptl: pthread_kill must send signals to a specific thread [BZ #28407]

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The choice between the kill vs tgkill system calls is not just about
the TID reuse race, but also about whether the signal is sent to the
whole process (and any thread in it) or to a specific thread.

This was caught by the openposix test suite:

  LTP: openposix test suite - FAIL: SIGUSR1 is member of new thread pendingset.
  <https://gitlab.com/cki-project/kernel-tests/-/issues/764>

Fixes commit 526c3cf11e ("nptl: Fix race
between pthread_kill and thread exit (bug 12889)").

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer
2021-10-01 18:16:41 +02:00
parent 176c88f521
commit eae81d7057
3 changed files with 94 additions and 3 deletions
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4
nptl/pthread_kill.c
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@@ -40,7 +40,7 @@ __pthread_kill_implementation (pthread_t threadid, int signo, int no_tid)
below. POSIX only guarantees delivery of a single signal,
which may not be the right one.) */
pid_t tid = INTERNAL_SYSCALL_CALL (gettid);
int ret = INTERNAL_SYSCALL_CALL (kill, tid, signo);
int ret = INTERNAL_SYSCALL_CALL (tgkill, __getpid (), tid, signo);
return INTERNAL_SYSCALL_ERROR_P (ret) ? INTERNAL_SYSCALL_ERRNO (ret) : 0;
}
@@ -59,8 +59,6 @@ __pthread_kill_implementation (pthread_t threadid, int signo, int no_tid)
ret = no_tid;
else
{
/* Using tgkill is a safety measure. pd->exit_lock ensures that
the target thread cannot exit. */
ret = INTERNAL_SYSCALL_CALL (tgkill, __getpid (), pd->tid, signo);
ret = INTERNAL_SYSCALL_ERROR_P (ret) ? INTERNAL_SYSCALL_ERRNO (ret) : 0;
}