From e1a5931827dc93c305204f71b37746bad3b6d5e7 Mon Sep 17 00:00:00 2001
From: Gerhard Rieger <gerhard@dest-unreach.org>
Date: Sun, 3 Mar 2019 09:32:22 +0100
Subject: [PATCH] Parent process might have been killed by signal to child

---
 CHANGES         |  5 +++++
 error.c         | 29 ++++++++++++++++++++++-------
 error.h         |  1 +
 test.sh         |  5 ++++-
 xioinitialize.c |  1 +
 5 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/CHANGES b/CHANGES
index 2b35f10..35e24c5 100644
--- a/CHANGES
+++ b/CHANGES
@@ -21,6 +21,11 @@ corrections:
 	Test: DIAG_FDIN
 	Problem reported by Onur Sentürk.
 
+	The socket based mechanism for passing messages and signal information
+	from signal handler to process could reach and kill the wrong process.
+	Introduces functions diag_sock_pair(), diag_fork()
+	Thanks to Darren Zhao for analysing and reporting this problem.
+
 testing:
 	test.sh: Show a warning when phase-1 (insecure phase) of a security
 	test fails
diff --git a/error.c b/error.c
index 7de3d39..b1ce8f6 100644
--- a/error.c
+++ b/error.c
@@ -110,15 +110,9 @@ static int diag_sock_recv = -1;
 static int diag_msg_avail = 0;	/* !=0: messages from within signal handler may be waiting */
 
 
-static int diag_init(void) {
+static int diag_sock_pair(void) {
    int handlersocks[2];
 
-   if (diaginitialized) {
-      return 0;
-   }
-   diaginitialized = 1;
-   /* gcc with GNU libc refuses to set this in the initializer */
-   diagopts.logfile = stderr;
    if (socketpair(AF_UNIX, SOCK_DGRAM, 0, handlersocks) < 0) {
       diag_sock_send = -1;
       diag_sock_recv = -1;
@@ -128,6 +122,19 @@ static int diag_init(void) {
    diag_sock_recv = handlersocks[0];
    return 0;
 }
+
+static int diag_init(void) {
+   if (diaginitialized) {
+      return 0;
+   }
+   diaginitialized = 1;
+   /* gcc with GNU libc refuses to set this in the initializer */
+   diagopts.logfile = stderr;
+   if (diag_sock_pair() < 0) {
+      return -1;
+   }
+   return 0;
+}
 #define DIAG_INIT ((void)(diaginitialized || diag_init()))
 
 
@@ -224,6 +231,14 @@ int diag_reserve_fd(int fd) {
    return 0;
 }
 
+/* call this after a fork() from the child process to separate master/parent
+   sockets from child sockets */
+int diag_fork() {
+   Close(diag_sock_send);
+   Close(diag_sock_recv);
+   return diag_sock_pair();
+}
+
 /* Linux and AIX syslog format:
 Oct  4 17:10:37 hostname socat[52798]: D signal(13, 1)
 */
diff --git a/error.h b/error.h
index d37982f..c6a3048 100644
--- a/error.h
+++ b/error.h
@@ -237,6 +237,7 @@ extern void diag_set_int(char what, int arg);
 extern int diag_get_int(char what);
 extern const char *diag_get_string(char what);
 extern int diag_reserve_fd(int fd);
+extern int diag_fork(void);
 extern int diag_dup(void);
 extern int diag_dup2(int newfd);
 extern void msg(int level, const char *format, ...);
diff --git a/test.sh b/test.sh
index 9f9787f..8c6590e 100755
--- a/test.sh
+++ b/test.sh
@@ -5449,7 +5449,10 @@ testserversec () {
 	esac
     else
 	$PRINTF "$OK\n"
-	if [ -n "$debug" ]; then cat $te; fi
+	[ "$VERBOSE" ] && echo "  $TRACE $SOCAT $opts $arg echo"
+	[ "$debug" ] && cat ${te}3
+	[ "$VERBOSE" ] && echo "  $TRACE $SOCAT $opts - $arg2"
+	[ "$debug" ] && cat ${te}4
 	numOK=$((numOK+1))
     fi
     wait
diff --git a/xioinitialize.c b/xioinitialize.c
index 29d7b03..a2b8cf6 100644
--- a/xioinitialize.c
+++ b/xioinitialize.c
@@ -178,6 +178,7 @@ int xio_forked_inchild(void) {
    int result = 0;
    int i;
 
+   diag_fork();
    for (i=0; i<NUMUNKNOWN; ++i) {
       diedunknown[i] = 0;
    }