[pve-devel] [PATCH cluster] fix #1559: pmxcfs: add missing lock when dumping .rrd

[Thomas Lamprecht]

Adding our standard mutex for protecting cfs_status from multiple
conflicting changes solves two things. First, it now protects
cfs_status as it was changed here and secondly, it protects the
global rrd_dump_buf and rrd_dump_last helper variables from
incosistent access and a double free chance.

Fixes: #1559
Reported-by: Tobias Böhm <tb at robhost.de>
Signed-off-by: Thomas Lamprecht <t.lamprecht at proxmox.com>
---
 data/src/status.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/data/src/status.c b/data/src/status.c
index 030c003..a73fa87 100644
--- a/data/src/status.c
+++ b/data/src/status.c
@@ -1076,10 +1076,13 @@ void
 cfs_rrd_dump(GString *str)
 {
 	time_t ctime;
+
+	g_mutex_lock (&mutex);
+
 	time(&ctime);
-
 	if (rrd_dump_buf && (ctime - rrd_dump_last) < 2) {
 		g_string_assign(str, rrd_dump_buf);
+		g_mutex_unlock (&mutex);
 		return;
 	}
 
@@ -1108,6 +1111,8 @@ cfs_rrd_dump(GString *str)
 	if (rrd_dump_buf)
 		g_free(rrd_dump_buf);
 	rrd_dump_buf = g_strdup(str->str);
+
+	g_mutex_unlock (&mutex);
 }
 
 static gboolean
-- 
2.11.0