[libvirt] [PATCH] qemuProcessCleanupChardevDevice: Don't unlink NULL paths

[Michal Privoznik]

So, you try to start a domain, but before we even get to the part
where chardev part of qemu command line is generated (and
possibly missing path to unix sockets is made up) an error occurs
which results in calling qemuProcessStop. This will then try to
clean up the mess and possibly ends up calling unlink(NULL).

==8085== Thread 3:
==8085== Syscall param unlink(pathname) points to unaddressable byte(s)
==8085==    at 0xA85EA57: unlink (in /lib64/libc-2.21.so)
==8085==    by 0x213D3C24: qemuProcessCleanupChardevDevice (qemu_process.c:2866)
==8085==    by 0x558D6B1: virDomainChrDefForeach (domain_conf.c:22924)
==8085==    by 0x213DA9AE: qemuProcessStop (qemu_process.c:5326)
==8085==    by 0x213DA2F2: qemuProcessStart (qemu_process.c:5190)
==8085==    by 0x2142957F: qemuDomainObjStart (qemu_driver.c:7396)
==8085==    by 0x214297DB: qemuDomainCreateWithFlags (qemu_driver.c:7450)
==8085==    by 0x21429842: qemuDomainCreate (qemu_driver.c:7468)
==8085==    by 0x5611B95: virDomainCreate (libvirt-domain.c:6753)
==8085==    by 0x125D9A: remoteDispatchDomainCreate (remote_dispatch.h:3613)
==8085==    by 0x125CB7: remoteDispatchDomainCreateHelper (remote_dispatch.h:3589)
==8085==    by 0x568BF41: virNetServerProgramDispatchCall (virnetserverprogram.c:437)
==8085==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==8085==

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_process.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 3d9e0e5..f083f3f 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -2862,7 +2862,8 @@ qemuProcessCleanupChardevDevice(virDomainDefPtr def ATTRIBUTE_UNUSED,
                                 void *opaque ATTRIBUTE_UNUSED)
 {
     if (dev->source.type == VIR_DOMAIN_CHR_TYPE_UNIX &&
-        dev->source.data.nix.listen)
+        dev->source.data.nix.listen &&
+        dev->source.data.nix.path)
         unlink(dev->source.data.nix.path);
 
     return 0;
-- 
2.4.10