hw/net/e1000e: advance desc_offset in case of null descriptor

[PATCH] hw/net/e1000e: advance desc_offset in case of null descriptor

Posted by P J P 3 years, 6 months ago

From: Prasad J Pandit <pjp@fedoraproject.org>

While receiving packets via e1000e_write_packet_to_guest() routine,
'desc_offset' is advanced only when RX descriptor is processed. And
RX descriptor is not processed if it has NULL buffer address.
This may lead to an infinite loop condition. Increament 'desc_offset'
to process next descriptor in the ring to avoid infinite loop.

Reported-by: Cheol-woo Myung <330cjfdn@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/net/e1000e_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
index bcfd46696f..3b096db3a4 100644
--- a/hw/net/e1000e_core.c
+++ b/hw/net/e1000e_core.c
@@ -1596,13 +1596,13 @@ e1000e_write_packet_to_guest(E1000ECore *core, struct NetRxPkt *pkt,
                           (const char *) &fcs_pad, e1000x_fcs_len(core->mac));
                 }
             }
-            desc_offset += desc_size;
-            if (desc_offset >= total_size) {
-                is_last = true;
-            }
         } else { /* as per intel docs; skip descriptors with null buf addr */
             trace_e1000e_rx_null_descriptor();
         }
+        desc_offset += desc_size;
+        if (desc_offset >= total_size) {
+            is_last = true;
+        }
 
         e1000e_write_rx_descr(core, desc, is_last ? core->rx_pkt : NULL,
                            rss_info, do_ps ? ps_hdr_len : 0, &bastate.written);
-- 
2.26.2

Re: [PATCH] hw/net/e1000e: advance desc_offset in case of null descriptor

Posted by Jason Wang 3 years, 6 months ago

On 2020/11/11 下午9:06, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
>
> While receiving packets via e1000e_write_packet_to_guest() routine,
> 'desc_offset' is advanced only when RX descriptor is processed. And
> RX descriptor is not processed if it has NULL buffer address.
> This may lead to an infinite loop condition. Increament 'desc_offset'
> to process next descriptor in the ring to avoid infinite loop.
>
> Reported-by: Cheol-woo Myung <330cjfdn@gmail.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>   hw/net/e1000e_core.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
> index bcfd46696f..3b096db3a4 100644
> --- a/hw/net/e1000e_core.c
> +++ b/hw/net/e1000e_core.c
> @@ -1596,13 +1596,13 @@ e1000e_write_packet_to_guest(E1000ECore *core, struct NetRxPkt *pkt,
>                             (const char *) &fcs_pad, e1000x_fcs_len(core->mac));
>                   }
>               }
> -            desc_offset += desc_size;
> -            if (desc_offset >= total_size) {
> -                is_last = true;
> -            }
>           } else { /* as per intel docs; skip descriptors with null buf addr */
>               trace_e1000e_rx_null_descriptor();
>           }
> +        desc_offset += desc_size;
> +        if (desc_offset >= total_size) {
> +            is_last = true;
> +        }
>   
>           e1000e_write_rx_descr(core, desc, is_last ? core->rx_pkt : NULL,
>                              rss_info, do_ps ? ps_hdr_len : 0, &bastate.written);


Applied.

Thanks