108 lines
3.1 KiB
Diff
108 lines
3.1 KiB
Diff
|
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Martin Wilck <mwilck@suse.com>
|
||
|
|
Date: Thu, 15 Oct 2020 16:13:14 +0200
|
||
|
|
Subject: [PATCH] libmultipath: fix race between log_safe and log_thread_stop()
|
||
|
|
|
||
|
|
log_safe() could race with log_thread_stop(); simply
|
||
|
|
checking the value of log_thr has never been safe. By converting the
|
||
|
|
mutexes to static initializers, we avoid having to destroy them, and thus
|
||
|
|
possibly accessing a destroyed mutex in log_safe(). Furthermore, taking
|
||
|
|
both the logev_lock and the logq_lock makes sure the logarea isn't freed
|
||
|
|
while we are writing to it.
|
||
|
|
|
||
|
|
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
|
||
|
|
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
|
||
|
|
---
|
||
|
|
libmultipath/log_pthread.c | 48 +++++++++++++++++++++-----------------
|
||
|
|
1 file changed, 26 insertions(+), 22 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/libmultipath/log_pthread.c b/libmultipath/log_pthread.c
|
||
|
|
index 3a2566ae..0d48c52c 100644
|
||
|
|
--- a/libmultipath/log_pthread.c
|
||
|
|
+++ b/libmultipath/log_pthread.c
|
||
|
|
@@ -17,31 +17,42 @@
|
||
|
|
|
||
|
|
static pthread_t log_thr;
|
||
|
|
|
||
|
|
-static pthread_mutex_t logq_lock;
|
||
|
|
-static pthread_mutex_t logev_lock;
|
||
|
|
-static pthread_cond_t logev_cond;
|
||
|
|
+/* logev_lock must not be taken with logq_lock held */
|
||
|
|
+static pthread_mutex_t logq_lock = PTHREAD_MUTEX_INITIALIZER;
|
||
|
|
+static pthread_mutex_t logev_lock = PTHREAD_MUTEX_INITIALIZER;
|
||
|
|
+static pthread_cond_t logev_cond = PTHREAD_COND_INITIALIZER;
|
||
|
|
|
||
|
|
static int logq_running;
|
||
|
|
static int log_messages_pending;
|
||
|
|
|
||
|
|
void log_safe (int prio, const char * fmt, va_list ap)
|
||
|
|
{
|
||
|
|
+ bool running;
|
||
|
|
+
|
||
|
|
if (prio > LOG_DEBUG)
|
||
|
|
prio = LOG_DEBUG;
|
||
|
|
|
||
|
|
- if (log_thr == (pthread_t)0) {
|
||
|
|
- vsyslog(prio, fmt, ap);
|
||
|
|
- return;
|
||
|
|
- }
|
||
|
|
+ /*
|
||
|
|
+ * logev_lock protects logq_running. By holding it, we avoid a race
|
||
|
|
+ * with log_thread_stop() -> log_close(), which would free the logarea.
|
||
|
|
+ */
|
||
|
|
+ pthread_mutex_lock(&logev_lock);
|
||
|
|
+ pthread_cleanup_push(cleanup_mutex, &logev_lock);
|
||
|
|
+ running = logq_running;
|
||
|
|
|
||
|
|
- pthread_mutex_lock(&logq_lock);
|
||
|
|
- log_enqueue(prio, fmt, ap);
|
||
|
|
- pthread_mutex_unlock(&logq_lock);
|
||
|
|
+ if (running) {
|
||
|
|
+ pthread_mutex_lock(&logq_lock);
|
||
|
|
+ pthread_cleanup_push(cleanup_mutex, &logq_lock);
|
||
|
|
+ log_enqueue(prio, fmt, ap);
|
||
|
|
+ pthread_cleanup_pop(1);
|
||
|
|
|
||
|
|
- pthread_mutex_lock(&logev_lock);
|
||
|
|
- log_messages_pending = 1;
|
||
|
|
- pthread_cond_signal(&logev_cond);
|
||
|
|
- pthread_mutex_unlock(&logev_lock);
|
||
|
|
+ log_messages_pending = 1;
|
||
|
|
+ pthread_cond_signal(&logev_cond);
|
||
|
|
+ }
|
||
|
|
+ pthread_cleanup_pop(1);
|
||
|
|
+
|
||
|
|
+ if (!running)
|
||
|
|
+ vsyslog(prio, fmt, ap);
|
||
|
|
}
|
||
|
|
|
||
|
|
static void flush_logqueue (void)
|
||
|
|
@@ -103,9 +114,6 @@ void log_thread_start (pthread_attr_t *attr)
|
||
|
|
int running = 0;
|
||
|
|
|
||
|
|
logdbg(stderr,"enter log_thread_start\n");
|
||
|
|
- pthread_mutex_init(&logq_lock, NULL);
|
||
|
|
- pthread_mutex_init(&logev_lock, NULL);
|
||
|
|
- pthread_cond_init(&logev_cond, NULL);
|
||
|
|
|
||
|
|
if (log_init("multipathd", 0)) {
|
||
|
|
fprintf(stderr,"can't initialize log buffer\n");
|
||
|
|
@@ -154,13 +162,9 @@ void log_thread_stop (void)
|
||
|
|
}
|
||
|
|
pthread_cleanup_pop(1);
|
||
|
|
|
||
|
|
- flush_logqueue();
|
||
|
|
if (running)
|
||
|
|
pthread_join(log_thr, NULL);
|
||
|
|
|
||
|
|
- pthread_mutex_destroy(&logq_lock);
|
||
|
|
- pthread_mutex_destroy(&logev_lock);
|
||
|
|
- pthread_cond_destroy(&logev_cond);
|
||
|
|
-
|
||
|
|
+ flush_logqueue();
|
||
|
|
log_close();
|
||
|
|
}
|
||
|
|
--
|
||
|
|
2.17.2
|
||
|
|
|