On Wed, Jan 23, 2013 at 05:25:32PM +0000, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
>
> The autodestroy callback code has the following function
> called from a hash iterator
>
> qemuDriverCloseCallbackRun(void *payload,
> const void *name,
> void *opaque)
> {
> ...
> char *uuidstr = name
> ...
>
> dom = closeDef->cb(data->driver, dom, data->conn);
> if (dom)
> virObjectUnlock(dom);
>
> virHashRemoveEntry(data->driver->closeCallbacks, uuidstr);
> }
>
> The closeDef->cb function may well cause the current callback
> to be removed, if it shuts down 'dom'. As such the use of
> 'uuidstr' in virHashRemoveEntry is accessing free'd memory.
> We must make a copy of the uuid str before invoking the
> callback to be safe.
>
> Signed-off-by: Daniel P. Berrange <berrange@xxxxxxxxxx>
> ---
> src/qemu/qemu_conf.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
> index b21392e..ee48333 100644
> --- a/src/qemu/qemu_conf.c
> +++ b/src/qemu/qemu_conf.c
> @@ -510,20 +510,25 @@ qemuDriverCloseCallbackRun(void *payload,
> {
> struct qemuDriverCloseCallbackData *data = opaque;
> qemuDriverCloseDefPtr closeDef = payload;
> - const char *uuidstr = name;
> unsigned char uuid[VIR_UUID_BUFLEN];
> + char uuidstr[VIR_UUID_STRING_BUFLEN];
> virDomainObjPtr dom;
>
> VIR_DEBUG("conn=%p, thisconn=%p, uuid=%s, cb=%p",
> - closeDef->conn, data->conn, uuidstr, closeDef->cb);
> + closeDef->conn, data->conn, (const char *)name, closeDef->cb);
>
> if (data->conn != closeDef->conn || !closeDef->cb)
> return;
>
> - if (virUUIDParse(uuidstr, uuid) < 0) {
> - VIR_WARN("Failed to parse %s", uuidstr);
> + if (virUUIDParse(name, uuid) < 0) {
> + VIR_WARN("Failed to parse %s", (const char *)name);
> return;
> }
> + /* We need to reformat uuidstr, because closeDef->cb
> + * might cause the current hash entry to be removed,
> + * which means 'name' will have been free()d
> + */
> + virUUIDFormat(uuid, uuidstr);
>
> if (!(dom = virDomainFindByUUID(&data->driver->domains, uuid))) {
> VIR_DEBUG("No domain object with UUID %s", uuidstr);
> --
> 1.8.1
Looks good, ACK.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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