Re: [libvirt] 1.2.0 segfault on Centos 6
On 02/04/2014 05:23 PM, Jiri Denemark wrote:
On Tue, Feb 04, 2014 at 17:02:41 +0100, Franky Van Liedekerke wrote:
> Hi,
>
> using libvirt 1.2.0 on a up-to-date Centos6.5 machine leads to
> occasional segmentation faults (see below).
> Sometimes it runs for 5 minutes, sometimes for an hour, but after that
> the result is always the same: segfault after some weird qom-list, that
> apparently the qemu version on centos doesn't know. Has 1.2.1 a known
> fix for this?
I believe the following patch should fix the crash. I'll do some testing
tomorrow and send it as a proper patch afterwards:
diff --git i/src/qemu/qemu_monitor.c w/src/qemu/qemu_monitor.c
index a968901..cdd817f 100644
--- i/src/qemu/qemu_monitor.c
+++ w/src/qemu/qemu_monitor.c
@@ -1019,7 +1019,9 @@ qemuMonitorFindBalloonObjectPath(qemuMonitorPtr mon,
virDomainObjPtr vm,
const char *curpath)
{
- size_t i, j, npaths = 0, nprops = 0;
+ size_t i, j;
+ int npaths = 0;
+ int nprops = 0;
Reading into what the contention of the issue is, then these are perhaps
all that's needed since the conflict is I assume the difference in size
between 'int' and 'size_t'. Perhaps something Eric Blake understands
best. My simple testing shows while difference in size (4 bytes vs. 8
bytes), the compiler seems to have done the right thing on the return
value (eg, assigning 'size_t' value to a function returning int of -1).
I know when I implemented this
http://www.redhat.com/archives/libvir-list/2013-July/msg00770.html
that I had tested without qom-list available.
Curious to know if the issue was seen in a provided or built libvirt.
It should be very simple to create a small C program that exhibits the
issue - just have a variable of size_t initialized to 0 that gets set by
a function that returns int, then print the result.
int ret = 0;
char *nextpath = NULL;
qemuMonitorJSONListPathPtr *paths = NULL;
@@ -1045,6 +1047,8 @@ qemuMonitorFindBalloonObjectPath(qemuMonitorPtr mon,
VIR_DEBUG("Searching for Balloon Object Path starting at %s", curpath);
npaths = qemuMonitorJSONGetObjectListPaths(mon, curpath, &paths);
+ if (npaths < 0)
+ return -1;
for (i = 0; i < npaths && ret == 0; i++) {
We wouldn't enter the loop in the 0 < -1 case, but would if 0 < 0x0000ffff
@@ -1061,6 +1065,11 @@ qemuMonitorFindBalloonObjectPath(qemuMonitorPtr mon,
* then this version of qemu/kvm does not support the feature.
*/
nprops = qemuMonitorJSONGetObjectListPaths(mon, nextpath, &bprops);
+ if (nprops < 0) {
+ ret = -1;
+ goto cleanup;
+ }
+
for (j = 0; j < nprops; j++) {
same here.
if (STREQ(bprops[j]->name,
"guest-stats-polling-interval")) {
VIR_DEBUG("Found Balloon Object Path %s", nextpath);
--
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