When searching qemuCaps->domCapsCache for existing domCaps data, we check for a matching pair of arch+virttype+machine+emulator. However for the hash table key we only use the machine string. So if the cache already contains: x86_64 + kvm + pc + /usr/bin/qemu-kvm But a new VM is defined with x86_64 + qemu + pc + /usr/bin/qemu-kvm We correctly fail to find matching cached domCaps, but then attempt to use a colliding key with virHashAddEntry Fix this by building a hash key from the 4 values, not just machine Signed-off-by: Cole Robinson <crobinso(a)redhat.com&gt; --- qemu_domain.c validation should be affected, but it is covered up by another bug, fixed here: https://www.redhat.com/archives/libvir-list/2019-October/msg00708.html src/qemu/qemu_conf.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c index 08cd784054..64ac8cbdd3 100644 --- a/src/qemu/qemu_conf.c +++ b/src/qemu/qemu_conf.c @@ -1396,6 +1396,8 @@ virQEMUDriverGetDomainCapabilities(virQEMUDriverPtr driver, domCaps = virHashSearch(domCapsCache, virQEMUDriverSearchDomcaps, &data, NULL); if (!domCaps) { + VIR_AUTOFREE(char *) key = NULL; + /* hash miss, build new domcaps */ if (!(domCaps = virDomainCapsNew(data.path, data.machine, data.arch, data.virttype))) @@ -1406,7 +1408,14 @@ virQEMUDriverGetDomainCapabilities(virQEMUDriverPtr driver, cfg->firmwares, cfg->nfirmwares) < 0) return NULL; - if (virHashAddEntry(domCapsCache, machine, domCaps) < 0) + if (virAsprintf(&key, "%d:%d:%s:%s", + data.arch, + data.virttype, + NULLSTR(data.machine), + NULLSTR(data.path)) < 0) + return NULL; + + if (virHashAddEntry(domCapsCache, key, domCaps) < 0) return NULL; } -- 2.23.0