From: Jean-Louis Fuchs <jean-louis.fuchs@adfinis-sygroup.ch>
Date: Mon, 28 Sep 2020 12:45:15 +0000 (+0200)
Subject: disable fork-malloc-exec for non-glibc-systems
X-Git-Tag: dbus-1.13.20~54^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3fab06d68f5940cde89fb9c7e647bdc48bc7b253;p=thirdparty%2Fdbus.git

disable fork-malloc-exec for non-glibc-systems

Calling malloc() after fork is undefined behaviour if the process is
multi-threaded. locks held by a thread on fork() will never be released.
malloc() is usally protected by a lock and can therefore deadlock. glibc
is known not to deadlock in this case.

This commit does not rule out other problems on glibc-systems, but fixes an
issue on musl-libc-systems. Only restricting to async-signal safe functions
between fork() and exec() prevents undefined behaviour for sure. See
signal-safety(7).
---

diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
index 0288dbc90..e585136f0 100644
--- a/dbus/dbus-sysdeps-unix.c
+++ b/dbus/dbus-sysdeps-unix.c
@@ -4742,7 +4742,7 @@ act_on_fds_3_and_up (void (*func) (int fd))
 {
   int maxfds, i;
 
-#ifdef __linux__
+#if defined(__linux__) && defined(__GLIBC__)
   DIR *d;
 
   /* On Linux we can optimize this a bit if /proc is available. If it