Re: [Qemu-devel] [PATCH 3/4] pcnet: fix Negative array index read

[Jason Wang]

On 11/20/2014 01:57 PM, address@hidden wrote:
> From: Gonglei <address@hidden>
>
> s->xmit_pos maybe assigned to a negative value (-1),
> but in this branch variable s->xmit_pos as an index to
> array s->buffer. Let's add a check for s->xmit_pos.
>
> Signed-off-by: Gonglei <address@hidden>
> ---
>  hw/net/pcnet.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
> index d344c15..2bb6417 100644
> --- a/hw/net/pcnet.c
> +++ b/hw/net/pcnet.c
> @@ -1247,7 +1247,7 @@ static void pcnet_transmit(PCNetState *s)
>              s->xmit_pos = -1;
>              goto txdone;
>          }
> -        if (!GET_FIELD(tmd.status, TMDS, ENP)) {
> +        if (!GET_FIELD(tmd.status, TMDS, ENP) && (s->xmit_pos >= 0)) {
>              int bcnt = 4096 - GET_FIELD(tmd.length, TMDL, BCNT);
>              s->phys_mem_read(s->dma_opaque, PHYSADDR(s, tmd.tbadr),
>                               s->buffer + s->xmit_pos, bcnt, CSR_BSWP(s));

Reviewed-by: Jason Wang <address@hidden>