Re: [Qemu-devel] [PATCH 14/16] cadence_gem: avoid stack-writing buffer-overrun

[Peter Crosthwaite]

I re-sent this yesterday to trivial.

May end up getting queued for merge twice.

On Tue, Jun 19, 2012 at 11:31 PM, Peter Maydell
<address@hidden> wrote:
> From: Jim Meyering <address@hidden>
>
> Use sizeof(rxbuf)-size (not sizeof(rxbuf-size)) as the number
> of bytes to clear.  The latter would always clear 4 or 8
> bytes, possibly writing beyond the end of that stack buffer.
> Alternatively, depending on the value of the "size" parameter,
> it could fail to initialize the end of "rxbuf".
> Spotted by coverity.
>
> Signed-off-by: Jim Meyering <address@hidden>
> Reviewed-by: Peter A.G. Crosthwaite <address@hidden>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  hw/cadence_gem.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/hw/cadence_gem.c b/hw/cadence_gem.c
> index e2140ae..dbde392 100644
> --- a/hw/cadence_gem.c
> +++ b/hw/cadence_gem.c
> @@ -664,7 +664,7 @@ static ssize_t gem_receive(VLANClientState *nc, const 
> uint8_t *buf, size_t size)
>          */
>
>         memcpy(rxbuf, buf, size);
> -        memset(rxbuf + size, 0, sizeof(rxbuf - size));
> +        memset(rxbuf + size, 0, sizeof(rxbuf) - size);
>         rxbuf_ptr = rxbuf;
>         crc_val = cpu_to_le32(crc32(0, rxbuf, MAX(size, 60)));
>         if (size < 60) {
> --
> 1.7.1
>
>