ch: Avoid memory leak in virCHProcessEvents()

The aim of virCHProcessEvents() is to read data (in JSON format)
from CH monitor and then process them. To parse incoming data
virJSONValueFromString() is used. But the corresponding
virJSONValue is freed only when processing of an even succeeds.
If processing an event fails, then the memory is not freed
leading to a memory leak.

334 (24 direct, 310 indirect) bytes in 1 blocks are definitely lost in loss record 1,975 of 2,040
   at 0x4919EF3: calloc (vg_replace_malloc.c:1675)
   by 0x4FEB249: g_malloc0 (in /usr/lib64/libglib-2.0.so.0.8400.3)
   by 0x4A66162: virJSONValueNewObject (virjson.c:533)
   by 0x4A67E74: virJSONValueFromJsonC (virjson.c:1413)
   by 0x4A681A5: virJSONValueFromString (virjson.c:1484)
   by 0xB8CD9D7: virCHProcessEvents (ch_events.c:179)
   by 0xB8CDCDC: virCHReadProcessEvents (ch_events.c:251)
   by 0xB8CDEBB: virCHEventHandlerLoop (ch_events.c:284)
   by 0x4AC1EB4: virThreadHelper (virthread.c:256)
   by 0x5441DE3: start_thread (in /usr/lib64/libc.so.6)
   by 0x54C25F3: clone (in /usr/lib64/libc.so.6)

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

diff --git a/src/ch/ch_events.c b/src/ch/ch_events.c
index be572dfde3e5d1cc2315dc2f0ba56aff26fd6fa7..25c7ecf90addb71d6205c9302651b96d5e9d397e 100644 (file)
--- a/src/ch/ch_events.c
+++ b/src/ch/ch_events.c
@@ -152,7 +152,6 @@ virCHProcessEvents(virCHMonitor *mon)
     virDomainObj *vm = mon->vm;
     char *buf = mon->event_buffer.buffer;
     ssize_t sz = mon->event_buffer.buf_fill_sz;
-    virJSONValue *obj = NULL;
     int blocks = 0;
     size_t i = 0;
     char *json_start;
@@ -168,6 +167,8 @@ virCHProcessEvents(virCHMonitor *mon)
         } else if (buf[i] == '}' && blocks > 0) {
             blocks--;
             if (blocks == 0) {
+                g_autoptr(virJSONValue) obj = NULL;
+
                 /* valid json document */
                 end_index = i;
 
@@ -182,7 +183,6 @@ virCHProcessEvents(virCHMonitor *mon)
                                   vm->def->name, json_start);
                         return -1;
                     }
-                    virJSONValueFree(obj);
                 } else {
                     VIR_ERROR(_("%1$s: Invalid JSON event doc: %2$s"),
                               vm->def->name, json_start);