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Re: [libvirt] [PATCH v2] qemu: Fix crash on failed VM startup



On Wed, Jun 02, 2010 at 10:55:17AM -0400, Cole Robinson wrote:
> If VM startup fails early enough (can't find a referenced USB device),
> libvirtd will crash trying to clear the VNC port bit, since port = 0,
> which overflows us out of the bitmap bounds.
> 
> Fix this by being more defensive in the bitmap operations, and only
> clearing a previously set VNC port.
> 
> v2: Add safety check to all relevant bitmap ops.
> 
> Signed-off-by: Cole Robinson <crobinso redhat com>
> ---
>  src/qemu/qemu_driver.c |    2 +-
>  src/util/bitmap.c      |    6 +++---
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index c8cd50a..f5a1310 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -3741,7 +3741,7 @@ retry:
>      if ((vm->def->ngraphics == 1) &&
>          vm->def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_VNC &&
>          vm->def->graphics[0]->data.vnc.autoport &&
> -        vm->def->graphics[0]->data.vnc.port != -1) {
> +        vm->def->graphics[0]->data.vnc.port >= QEMU_VNC_PORT_MIN) {
>          if (virBitmapClearBit(driver->reservedVNCPorts,
>                                vm->def->graphics[0]->data.vnc.port - \
>                                QEMU_VNC_PORT_MIN) < 0) {
> diff --git a/src/util/bitmap.c b/src/util/bitmap.c
> index 69094a5..cef3fc4 100644
> --- a/src/util/bitmap.c
> +++ b/src/util/bitmap.c
> @@ -100,7 +100,7 @@ void virBitmapFree(virBitmapPtr bitmap)
>   */
>  int virBitmapSetBit(virBitmapPtr bitmap, size_t b)
>  {
> -    if (b > bitmap->size - 1)
> +    if (bitmap->size <= b)
>          return -1;
>  
>      bitmap->map[VIR_BITMAP_UNIT_OFFSET(b)] |= (1 << VIR_BITMAP_BIT_OFFSET(b));
> @@ -118,7 +118,7 @@ int virBitmapSetBit(virBitmapPtr bitmap, size_t b)
>   */
>  int virBitmapClearBit(virBitmapPtr bitmap, size_t b)
>  {
> -    if (b > bitmap->size - 1)
> +    if (bitmap->size <= b)
>          return -1;
>  
>      bitmap->map[VIR_BITMAP_UNIT_OFFSET(b)] &= ~(1 << VIR_BITMAP_BIT_OFFSET(b));
> @@ -140,7 +140,7 @@ int virBitmapGetBit(virBitmapPtr bitmap, size_t b, bool *result)
>  {
>      uint32_t bit;
>  
> -    if (b > bitmap->size - 1)
> +    if (bitmap->size <= b)
>          return -1;
>  
>      bit = bitmap->map[VIR_BITMAP_UNIT_OFFSET(b)] &

ACK, this patch doesn't seem to have ever been pushed - current GIT still
crashes on abort of VM startup

Daniel
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