[Qemu-devel] Re: [PATCH RFC] e1000: fix access 4 bytes beyond buffer end

[Alex Williamson]

On Mon, 2010-07-12 at 20:48 +0300, Michael S. Tsirkin wrote:
> We do range check for size, and get size as buffer,
> but copy size + 4 bytes (4 is for FCS).
> Let's copy size bytes but put size + 4 in length.
> 
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
> 
> Anthony, Alex, please review.

Looks fine to me.

Acked-by: Alex Williamson <address@hidden>

>  hw/e1000.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/e1000.c b/hw/e1000.c
> index 0da65f9..70aba11 100644
> --- a/hw/e1000.c
> +++ b/hw/e1000.c
> @@ -649,7 +649,6 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, 
> size_t size)
>      }
>  
>      rdh_start = s->mac_reg[RDH];
> -    size += 4; // for the header
>      do {
>          if (s->mac_reg[RDH] == s->mac_reg[RDT] && s->check_rxov) {
>              set_ics(s, 0, E1000_ICS_RXO);
> @@ -663,7 +662,7 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, 
> size_t size)
>          if (desc.buffer_addr) {
>              cpu_physical_memory_write(le64_to_cpu(desc.buffer_addr),
>                                        (void *)(buf + vlan_offset), size);
> -            desc.length = cpu_to_le16(size);
> +            desc.length = cpu_to_le16(size + 4 /* for FCS */);
>              desc.status |= E1000_RXD_STAT_EOP|E1000_RXD_STAT_IXSM;
>          } else // as per intel docs; skip descriptors with null buf addr
>              DBGOUT(RX, "Null RX descriptor!!\n");