[libvirt] [PATCH] qemu: Fix crash when using shared cdrom or floppy disk without source

Daniel P. Berrange berrange at redhat.com
Thu Feb 7 13:08:02 UTC 2013


On Thu, Feb 07, 2013 at 09:04:18PM +0800, Osier Yang wrote:
> How to reproduce the crash:
> 
>   * Start a guest with a disk like:
> 
>     <disk type='block' device='cdrom'>
>       <driver name='qemu' type='raw'/>
>       <target dev='hdc' bus='ide'/>
>       <readonly/>
>       <shareable/>
>       <address type='drive' controller='0' bus='1' target='0' unit='0'/>
>     </disk>
> 
> It's caused by disk->src for this disk is NULL. This patch fixes it.
> ---
>  src/qemu/qemu_process.c |    8 ++++++--
>  1 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index a2ce007..d1872c0 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -3837,7 +3837,9 @@ int qemuProcessStart(virConnectPtr conn,
>                             _("Raw I/O is not supported on this platform"));
>  #endif
>  
> -        if (disk->type == VIR_DOMAIN_DISK_TYPE_BLOCK && disk->shared) {
> +        if (disk->type == VIR_DOMAIN_DISK_TYPE_BLOCK &&
> +            disk->shared &&
> +            disk->src) {
>              if (qemuAddSharedDisk(driver->sharedDisks, disk->src) < 0)
>                  goto cleanup;
>  
> @@ -4246,7 +4248,9 @@ void qemuProcessStop(virQEMUDriverPtr driver,
>      for (i = 0; i < vm->def->ndisks; i++) {
>          virDomainDiskDefPtr disk = vm->def->disks[i];
>  
> -        if (disk->type == VIR_DOMAIN_DISK_TYPE_BLOCK && disk->shared) {
> +        if (disk->type == VIR_DOMAIN_DISK_TYPE_BLOCK &&
> +            disk->shared &&
> +            disk->src) {
>              ignore_value(qemuRemoveSharedDisk(driver->sharedDisks, disk->src));
>          }
>      }

ACK, though this isn't the only crash in this code - the crash I reported
occurs when you issue a 'change media' request on a CDROM.

Daniel
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