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Ignore interception of the SIGCHLD signals. 

SIGCHLD once blocked is discarded by the kernel as it has the
SA_IGNORE property. During the fork(2) operation all signals can be
shortly blocked and missed (unless there is a registered signal
handler in the traced child). This leads to a race in this test if
there would be an intention to catch SIGCHLD.

Fixes PR lib/55241 by Andreas Gustafsson
This commit is contained in:
kamil 2020-05-14 19:21:35 +00:00
parent 76fee9e5d6
commit 1cb4f56df8
1 changed files with 15 additions and 11 deletions
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26
tests/lib/libc/sys/t_ptrace_fork_wait.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: t_ptrace_fork_wait.h,v 1.2 2020/05/11 20:58:48 kamil Exp $ */
/* $NetBSD: t_ptrace_fork_wait.h,v 1.3 2020/05/14 19:21:35 kamil Exp $ */
/*-
* Copyright (c) 2016, 2017, 2018, 2020 The NetBSD Foundation, Inc.
@ -38,6 +38,7 @@ fork_body(const char *fn, bool trackspawn, bool trackfork, bool trackvfork,
#if defined(TWAIT_HAVE_STATUS)
int status;
#endif
sigset_t set;
ptrace_state_t state;
const int slen = sizeof(state);
ptrace_event_t event;
@ -98,6 +99,19 @@ fork_body(const char *fn, bool trackspawn, bool trackfork, bool trackvfork,
event.pe_set_event |= PTRACE_VFORK_DONE;
SYSCALL_REQUIRE(ptrace(PT_SET_EVENT_MASK, child, &event, elen) != -1);
/*
* Ignore interception of the SIGCHLD signals.
*
* SIGCHLD once blocked is discarded by the kernel as it has the
* SA_IGNORE property. During the fork(2) operation all signals can be
* shortly blocked and missed (unless there is a registered signal
* handler in the traced child). This leads to a race in this test if
* there would be an intention to catch SIGCHLD.
*/
sigemptyset(&set);
sigaddset(&set, SIGCHLD);
SYSCALL_REQUIRE(ptrace(PT_SET_SIGPASS, child, &set, sizeof(set)) != -1);
DPRINTF("Before resuming the child process where it left off and "
"without signal to be sent\n");
SYSCALL_REQUIRE(ptrace(PT_CONTINUE, child, (void *)1, 0) != -1);
@ -207,16 +221,6 @@ fork_body(const char *fn, bool trackspawn, bool trackfork, bool trackvfork,
}
#endif
DPRINTF("Before calling %s() for the child - expected stopped "
"SIGCHLD\n", TWAIT_FNAME);
TWAIT_REQUIRE_SUCCESS(wpid = TWAIT_GENERIC(child, &status, 0), child);
validate_status_stopped(status, SIGCHLD);
DPRINTF("Before resuming the child process where it left off and "
"without signal to be sent\n");
SYSCALL_REQUIRE(ptrace(PT_CONTINUE, child, (void *)1, 0) != -1);
DPRINTF("Before calling %s() for the child - expected exited\n",
TWAIT_FNAME);
TWAIT_REQUIRE_SUCCESS(wpid = TWAIT_GENERIC(child, &status, 0), child);