Re: [Qemu-devel] [PATCH] acpi: fix buffer overrun on migration

[John Snow <jsnow@redhat.com>]

On 11/19/2015 08:35 AM, Michael S. Tsirkin wrote:
> ich calls acpi_gpe_init with length ICH9_PMIO_GPE0_LEN so
> ICH9_PMIO_GPE0_LEN/2 bytes are allocated, but then the full
> ICH9_PMIO_GPE0_LEN bytes are migrated.
> 
> As a quick work-around, allocate twice the memory.
> We'll probably want to tweak code to avoid
> migrating the extra ICH9_PMIO_GPE0_LEN/2 bytes,
> but that is a bit trickier to do without breaking
> migration compatibility.
> 
> Tested-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/acpi/core.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/acpi/core.c b/hw/acpi/core.c
> index fe6215a..21e113d 100644
> --- a/hw/acpi/core.c
> +++ b/hw/acpi/core.c
> @@ -625,8 +625,12 @@ void acpi_pm1_cnt_reset(ACPIREGS *ar)
>  void acpi_gpe_init(ACPIREGS *ar, uint8_t len)
>  {
>      ar->gpe.len = len;
> -    ar->gpe.sts = g_malloc0(len / 2);
> -    ar->gpe.en = g_malloc0(len / 2);
> +    /* Only first len / 2 bytes are ever used,
> +     * but the caller in ich9.c migrates full len bytes.
> +     * TODO: fix ich9.c and drop the extra allocation.
> +     */
> +    ar->gpe.sts = g_malloc0(len);
> +    ar->gpe.en = g_malloc0(len);
>  }
>  
>  void acpi_gpe_reset(ACPIREGS *ar)
> 

Reviewed-by: John Snow <jsnow@redhat.com>