device-mapper-multipath/0078-libmultipath-protect-logarea-with-logq_lock.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Martin Wilck <mwilck@suse.com>
Date: Mon, 26 Oct 2020 22:13:40 +0100
Subject: [PATCH] libmultipath: protect logarea with logq_lock

Make sure the global logarea (la) is only allocated and freed
hile holding logq_lock. This avoids invalid memory access.

This patch makes free_logarea() static. libmultipath.version
is unchanged, as free_logarea() wasn't exported anyway.
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 libmultipath/log.c | 32 +++++++++++++++++++++++---------
 libmultipath/log.h |  1 -
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/libmultipath/log.c b/libmultipath/log.c
index 7f337879..95c8f01a 100644
--- a/libmultipath/log.c
+++ b/libmultipath/log.c
@@ -77,16 +77,23 @@ static int logarea_init (int size)
 
 int log_init(char *program_name, int size)
 {
+	int ret = 1;
+
 	logdbg(stderr,"enter log_init\n");
+
+	pthread_mutex_lock(&logq_lock);
+	pthread_cleanup_push(cleanup_mutex, &logq_lock);
+
 	openlog(program_name, 0, LOG_DAEMON);
+	if (!la)
+		ret = logarea_init(size);
 
-	if (logarea_init(size))
-		return 1;
+	pthread_cleanup_pop(1);
 
-	return 0;
+	return ret;
 }
 
-void free_logarea (void)
+static void free_logarea (void)
 {
 	FREE(la->start);
 	FREE(la->buff);
@@ -96,9 +103,14 @@ void free_logarea (void)
 
 void log_close (void)
 {
-	free_logarea();
+	pthread_mutex_lock(&logq_lock);
+	pthread_cleanup_push(cleanup_mutex, &logq_lock);
+
+	if (la)
+		free_logarea();
 	closelog();
 
+	pthread_cleanup_pop(1);
 	return;
 }
 
@@ -175,11 +187,12 @@ static int _log_enqueue(int prio, const char * fmt, va_list ap)
 
 int log_enqueue(int prio, const char *fmt, va_list ap)
 {
-	int ret;
+	int ret = 1;
 
 	pthread_mutex_lock(&logq_lock);
 	pthread_cleanup_push(cleanup_mutex, &logq_lock);
-	ret = _log_enqueue(prio, fmt, ap);
+	if (la)
+		ret = _log_enqueue(prio, fmt, ap);
 	pthread_cleanup_pop(1);
 	return ret;
 }
@@ -215,11 +228,12 @@ static int _log_dequeue(void *buff)
 
 int log_dequeue(void *buff)
 {
-	int ret;
+	int ret = 1;
 
 	pthread_mutex_lock(&logq_lock);
 	pthread_cleanup_push(cleanup_mutex, &logq_lock);
-	ret = _log_dequeue(buff);
+	if (la)
+		ret = _log_dequeue(buff);
 	pthread_cleanup_pop(1);
 	return ret;
 }
diff --git a/libmultipath/log.h b/libmultipath/log.h
index d2448f6a..fa224e4d 100644
--- a/libmultipath/log.h
+++ b/libmultipath/log.h
@@ -39,6 +39,5 @@ int log_enqueue (int prio, const char * fmt, va_list ap)
 int log_dequeue (void *);
 void log_syslog (void *);
 void dump_logmsg (void *);
-void free_logarea (void);
 
 #endif /* LOG_H */
-- 
2.17.2