From 1bcf431f2d0ed972d7f25f71e559e2c8fcd200df Mon Sep 17 00:00:00 2001
From: Mike Christie <michaelc@cs.wisc.edu>
Date: Mon, 7 Dec 2009 10:50:15 -0600
Subject: [PATCH] do not use a semarg in shared-mem for semop calls

From guy keren:
each process must have its own semarg structure - or they step on each
others'
toes - which could cause either deadlocks or smearing of the shared
memory
protected by the semaphore.

Signed-off-by: guy keren <choo@actcom.co.il>

diff --git a/usr/log.c b/usr/log.c
index 0fb1595..08a33de 100644
--- a/usr/log.c
+++ b/usr/log.c
@@ -261,16 +261,21 @@ static void log_syslog (void * buff)
 static void dolog(int prio, const char *fmt, va_list ap)
 {
 	if (log_daemon) {
-		la->ops[0].sem_op = -1;
-		if (semop(la->semid, la->ops, 1) < 0) {
+		struct sembuf ops[1];
+
+		ops[0].sem_num = la->ops[0].sem_num;
+		ops[0].sem_flg = la->ops[0].sem_flg;
+
+		ops[0].sem_op = -1;
+		if (semop(la->semid, ops, 1) < 0) {
 			syslog(LOG_ERR, "semop up failed %d", errno);
 			return;
 		}
 
 		log_enqueue(prio, fmt, ap);
 
-		la->ops[0].sem_op = 1;
-		if (semop(la->semid, la->ops, 1) < 0) {
+		ops[0].sem_op = 1;
+		if (semop(la->semid, ops, 1) < 0) {
 			syslog(LOG_ERR, "semop down failed");
 			return;
 		}
@@ -347,16 +352,21 @@ static void __dump_char(int level, unsigned char *buf, int *cp, int ch)
 static void log_flush(void)
 {
 	int msglen;
+	struct sembuf ops[1];
+
+	ops[0].sem_num = la->ops[0].sem_num;
+	ops[0].sem_flg = la->ops[0].sem_flg;
+
 
 	while (!la->empty) {
-		la->ops[0].sem_op = -1;
-		if (semop(la->semid, la->ops, 1) < 0) {
+		ops[0].sem_op = -1;
+		if (semop(la->semid, ops, 1) < 0) {
 			syslog(LOG_ERR, "semop up failed %d", errno);
 			exit(1);
 		}
 		msglen = log_dequeue(la->buff);
-		la->ops[0].sem_op = 1;
-		if (semop(la->semid, la->ops, 1) < 0) {
+		ops[0].sem_op = 1;
+		if (semop(la->semid, ops, 1) < 0) {
 			syslog(LOG_ERR, "semop down failed");
 			exit(1);
 		}