From: Jim Fehlig <[email protected]>
Date: Tue, 11 Apr 2023 09:15:43 -0600
Subject: [PATCH] qemu: Fix potential crash during driver cleanup

During qemu driver shutdown, objects are freed in qemuStateCleanup that
could still be used by active worker threads, resulting in crashes. E.g.
a worker thread could be processing a monitor EOF event after the
security manager is already disposed

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007fd9a9a1e1fe in virSecurityManagerMoveImageMetadata (mgr=0x7fd948012160, pid=-1, src=src@entry=0x7fd98c072c90, dst=dst@entry=0x0)
    at ../../src/security/security_manager.c:468
#1  0x00007fd9646ff0f0 in qemuSecurityMoveImageMetadata (driver=driver@entry=0x7fd948043830, vm=vm@entry=0x7fd98c066db0, src=src@entry=0x7fd98c072c90,
    dst=dst@entry=0x0) at ../../src/qemu/qemu_security.c:182
#2  0x00007fd96462c7b0 in qemuBlockRemoveImageMetadata (driver=driver@entry=0x7fd948043830, vm=vm@entry=0x7fd98c066db0, diskTarget=0x7fd98c072530 "vda",
    src=<optimized out>) at ../../src/qemu/qemu_block.c:2628
#3  0x00007fd9646929d6 in qemuProcessStop (driver=driver@entry=0x7fd948043830, vm=vm@entry=0x7fd98c066db0, reason=reason@entry=VIR_DOMAIN_SHUTOFF_SHUTDOWN,
    asyncJob=asyncJob@entry=QEMU_ASYNC_JOB_NONE, flags=<optimized out>) at ../../src/qemu/qemu_process.c:7585
#4  0x00007fd9646fc842 in processMonitorEOFEvent (vm=0x7fd98c066db0, driver=0x7fd948043830) at ../../src/qemu/qemu_driver.c:4794
#5  qemuProcessEventHandler (data=0x561a93febb60, opaque=0x7fd948043830) at ../../src/qemu/qemu_driver.c:4900
#6  0x00007fd9a9971a31 in virThreadPoolWorker (opaque=opaque@entry=0x561a93fb58e0) at ../../src/util/virthreadpool.c:163
(gdb) p mgr->drv
$2 = (virSecurityDriverPtr) 0x0

Prior to commit 7cf76d4e3ab, the worker thread pool was freed before
disposing any driver objects. Let's return to that pattern, but leave
the other changes made by 7cf76d4e3ab.

Signed-off-by: Tamara Schmitz <[email protected]>
Signed-off-by: Jim Fehlig <[email protected]>
Reviewed-by: Martin Kletzander <[email protected]>
---
 src/qemu/qemu_driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 32b3ef3..7a70d6c 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -1120,6 +1120,7 @@ qemuStateCleanup(void)
     if (!qemu_driver)
         return -1;
 
+    virThreadPoolFree(qemu_driver->workerPool);
     virObjectUnref(qemu_driver->migrationErrors);
     virObjectUnref(qemu_driver->closeCallbacks);
     virLockManagerPluginUnref(qemu_driver->lockManager);
@@ -1139,7 +1140,6 @@ qemuStateCleanup(void)
     ebtablesContextFree(qemu_driver->ebtables);
     VIR_FREE(qemu_driver->qemuImgBinary);
     virObjectUnref(qemu_driver->domains);
-    virThreadPoolFree(qemu_driver->workerPool);
 
     if (qemu_driver->lockFD != -1)
         virPidFileRelease(qemu_driver->config->stateDir, "driver", qemu_driver->lockFD);
-- 
2.33.0