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From fbcd6c97015324480f843c08da338c9d580b2b31 Mon Sep 17 00:00:00 2001
From: Phil Sutter <psutter@redhat.com>
Date: Fri, 15 Mar 2019 17:51:28 +0100
Subject: [PATCH] libxtables: Use posix_spawn() instead of vfork()
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1525980
Upstream Status: iptables commit d95c1e8b65c4e
commit d95c1e8b65c4ec66b8fcd2f7ede257853a888750
Author: Phil Sutter <phil@nwl.cc>
Date: Wed Sep 19 15:17:05 2018 +0200
libxtables: Use posix_spawn() instead of vfork()
According to covscan, vfork() may lead to a deadlock in the parent
process. It suggests to use posix_spawn() instead. Since the latter
combines vfork() and exec() calls, use it for xtables_insmod().
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Phil Sutter <psutter@redhat.com>
---
libxtables/xtables.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff --git a/libxtables/xtables.c b/libxtables/xtables.c
index bca9863acc566..7210d3706bf26 100644
--- a/libxtables/xtables.c
+++ b/libxtables/xtables.c
@@ -21,6 +21,7 @@
#include <fcntl.h>
#include <inttypes.h>
#include <netdb.h>
+#include <spawn.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
@@ -343,6 +344,7 @@ int xtables_insmod(const char *modname, const char *modprobe, bool quiet)
char *buf = NULL;
char *argv[4];
int status;
+ pid_t pid;
/* If they don't explicitly set it, read out of kernel */
if (!modprobe) {
@@ -363,18 +365,11 @@ int xtables_insmod(const char *modname, const char *modprobe, bool quiet)
*/
fflush(stdout);
- switch (vfork()) {
- case 0:
- execv(argv[0], argv);
-
- /* not usually reached */
- _exit(1);
- case -1:
+ if (posix_spawn(&pid, argv[0], NULL, NULL, argv, NULL)) {
free(buf);
return -1;
-
- default: /* parent */
- wait(&status);
+ } else {
+ waitpid(pid, &status, 0);
}
free(buf);
--
2.21.0