Thu Apr 16 14:39:58 2020 UTC ()
Introduce intermediate locking for fork, so that the dynamic linker is
in a consistent state. This most importantly avoids races between dlopen
and friends and fork, potentially resulting in dead locks in the child
when it itself tries to acquire locks.
(joerg)
diff -r1.12 -r1.13 src/lib/libc/gen/pthread_atfork.c
diff -r1.203 -r1.204 src/libexec/ld.elf_so/rtld.c
diff -r1.138 -r1.139 src/libexec/ld.elf_so/rtld.h
diff -r1.2 -r1.3 src/libexec/ld.elf_so/symbols.map
--- src/lib/libc/gen/pthread_atfork.c 2020/02/01 18:14:16 1.12
+++ src/lib/libc/gen/pthread_atfork.c 2020/04/16 14:39:58 1.13
@@ -1,4 +1,4 @@
-/* $NetBSD: pthread_atfork.c,v 1.12 2020/02/01 18:14:16 kamil Exp $ */
+/* $NetBSD: pthread_atfork.c,v 1.13 2020/04/16 14:39:58 joerg Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: pthread_atfork.c,v 1.12 2020/02/01 18:14:16 kamil Exp $");
+__RCSID("$NetBSD: pthread_atfork.c,v 1.13 2020/04/16 14:39:58 joerg Exp $");
#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
@@ -48,7 +48,14 @@
#endif /* __weak_alias */
pid_t __fork(void); /* XXX */
+pid_t __atomic_fork(void) __weak; /* XXX */
+pid_t
+__atomic_fork(void)
+{
+ return __fork();
+}
+
struct atfork_callback {
SIMPLEQ_ENTRY(atfork_callback) next;
void (*fn)(void);
@@ -157,7 +164,7 @@
SIMPLEQ_FOREACH(iter, &prepareq, next)
(*iter->fn)();
- ret = __fork();
+ ret = __atomic_fork();
if (ret != 0) {
/*
--- src/libexec/ld.elf_so/rtld.c 2020/03/04 01:21:17 1.203
+++ src/libexec/ld.elf_so/rtld.c 2020/04/16 14:39:58 1.204
@@ -1,4 +1,4 @@
-/* $NetBSD: rtld.c,v 1.203 2020/03/04 01:21:17 thorpej Exp $ */
+/* $NetBSD: rtld.c,v 1.204 2020/04/16 14:39:58 joerg Exp $ */
/*
* Copyright 1996 John D. Polstra.
@@ -40,7 +40,7 @@
#include <sys/cdefs.h>
#ifndef lint
-__RCSID("$NetBSD: rtld.c,v 1.203 2020/03/04 01:21:17 thorpej Exp $");
+__RCSID("$NetBSD: rtld.c,v 1.204 2020/04/16 14:39:58 joerg Exp $");
#endif /* not lint */
#include <sys/param.h>
@@ -1530,6 +1530,21 @@
}
_rtld_exclusive_exit(&mask);
+}
+
+pid_t __fork(void);
+
+__dso_public pid_t
+__atomic_fork(void)
+{
+ sigset_t mask;
+ pid_t result;
+
+ _rtld_exclusive_enter(&mask);
+ result = __fork();
+ _rtld_exclusive_exit(&mask);
+
+ return result;
}
/*
--- src/libexec/ld.elf_so/rtld.h 2020/02/29 04:24:33 1.138
+++ src/libexec/ld.elf_so/rtld.h 2020/04/16 14:39:58 1.139
@@ -1,4 +1,4 @@
-/* $NetBSD: rtld.h,v 1.138 2020/02/29 04:24:33 kamil Exp $ */
+/* $NetBSD: rtld.h,v 1.139 2020/04/16 14:39:58 joerg Exp $ */
/*
* Copyright 1996 John D. Polstra.
@@ -369,6 +369,8 @@
__dso_public void *_dlauxinfo(void) __pure;
__dso_public void __dl_cxa_refcount(void *addr, ssize_t delta);
+
+__dso_public pid_t __atomic_fork(void);
#if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
/*
--- src/libexec/ld.elf_so/symbols.map 2017/07/11 15:21:35 1.2
+++ src/libexec/ld.elf_so/symbols.map 2020/04/16 14:39:58 1.3
@@ -23,5 +23,6 @@
___tls_get_addr;
__gnu_Unwind_Find_exidx;
__dl_cxa_refcount;
+ __atomic_fork;
local: *;
};