Module Name: src
Committed By: joerg
Date: Thu Apr 16 14:39:58 UTC 2020
Modified Files:
src/lib/libc/gen: pthread_atfork.c
src/libexec/ld.elf_so: rtld.c rtld.h symbols.map
Log Message:
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.
To generate a diff of this commit:
cvs rdiff -u -r1.12 -r1.13 src/lib/libc/gen/pthread_atfork.c
cvs rdiff -u -r1.203 -r1.204 src/libexec/ld.elf_so/rtld.c
cvs rdiff -u -r1.138 -r1.139 src/libexec/ld.elf_so/rtld.h
cvs rdiff -u -r1.2 -r1.3 src/libexec/ld.elf_so/symbols.map
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/gen/pthread_atfork.c
diff -u src/lib/libc/gen/pthread_atfork.c:1.12 src/lib/libc/gen/pthread_atfork.c:1.13
--- src/lib/libc/gen/pthread_atfork.c:1.12 Sat Feb 1 18:14:16 2020
+++ src/lib/libc/gen/pthread_atfork.c Thu Apr 16 14:39:58 2020
@@ -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"
@@ -48,6 +48,13 @@ __weak_alias(fork, _fork)
#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;
@@ -157,7 +164,7 @@ fork(void)
SIMPLEQ_FOREACH(iter, &prepareq, next)
(*iter->fn)();
- ret = __fork();
+ ret = __atomic_fork();
if (ret != 0) {
/*
Index: src/libexec/ld.elf_so/rtld.c
diff -u src/libexec/ld.elf_so/rtld.c:1.203 src/libexec/ld.elf_so/rtld.c:1.204
--- src/libexec/ld.elf_so/rtld.c:1.203 Wed Mar 4 01:21:17 2020
+++ src/libexec/ld.elf_so/rtld.c Thu Apr 16 14:39:58 2020
@@ -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>
@@ -1532,6 +1532,21 @@ __dl_cxa_refcount(void *addr, ssize_t de
_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;
+}
+
/*
* Error reporting function. Use it like printf. If formats the message
* into a buffer, and sets things up so that the next call to dlerror()
Index: src/libexec/ld.elf_so/rtld.h
diff -u src/libexec/ld.elf_so/rtld.h:1.138 src/libexec/ld.elf_so/rtld.h:1.139
--- src/libexec/ld.elf_so/rtld.h:1.138 Sat Feb 29 04:24:33 2020
+++ src/libexec/ld.elf_so/rtld.h Thu Apr 16 14:39:58 2020
@@ -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.
@@ -370,6 +370,8 @@ __dso_public int dl_iterate_phdr(int (*)
__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__)
/*
* This is used by libgcc to find the start and length of the exception table
Index: src/libexec/ld.elf_so/symbols.map
diff -u src/libexec/ld.elf_so/symbols.map:1.2 src/libexec/ld.elf_so/symbols.map:1.3
--- src/libexec/ld.elf_so/symbols.map:1.2 Tue Jul 11 15:21:35 2017
+++ src/libexec/ld.elf_so/symbols.map Thu Apr 16 14:39:58 2020
@@ -23,5 +23,6 @@
___tls_get_addr;
__gnu_Unwind_Find_exidx;
__dl_cxa_refcount;
+ __atomic_fork;
local: *;
};
