On 31/05/2016 19:53, P J P wrote:
> From: Prasad J Pandit <p...@fedoraproject.org>
>
> The 53C9X Fast SCSI Controller(FSC) comes with an internal 16-byte
> FIFO buffer. It is used to handle command and data transfer.
> Routine get_cmd() in non-DMA mode, uses 'ti_size' to read scsi
> command into a buffer. Add check to validate command length against
> buffer size to avoid any overrun.
>
> Reported-by: Li Qiang <liqiang...@360.cn>
> Signed-off-by: Prasad J Pandit <p...@fedoraproject.org>
> ---
> hw/scsi/esp.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
> index 60c1b28..953027a 100644
> --- a/hw/scsi/esp.c
> +++ b/hw/scsi/esp.c
> @@ -98,6 +98,9 @@ static uint32_t get_cmd(ESPState *s, uint8_t *buf, uint8_t
> buflen)
> s->dma_memory_read(s->dma_opaque, buf, dmalen);
> } else {
> dmalen = s->ti_size;
> + if (dmalen > TI_BUFSZ) {
> + return 0;
> + }
> memcpy(buf, s->ti_buf, dmalen);
> buf[0] = buf[2] >> 5;
> }
>
In theory this shouldn't happen, but I agree that it is better to be
defensive. I'm queuing this patch.
At least the following patch is needed to ensure that ti_size always
matches ti_rptr/ti_wptr (Hervé, what do you think about it? should I
resubmit it formally?). Also, things are more complicated than
necessary due to ti_size being used for both DMA and FIFO transfers.
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index c2f6f8f..6407844 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -222,7 +222,7 @@ static void write_response(ESPState *s)
} else {
s->ti_size = 2;
s->ti_rptr = 0;
- s->ti_wptr = 0;
+ s->ti_wptr = 2;
s->rregs[ESP_RFLAGS] = 2;
}
esp_raise_irq(s);
Paolo
