* [PATCH v2] net/tap: drop too small packets
@ 2025-07-16 7:28 Vladimir Sementsov-Ogievskiy
2025-07-18 8:28 ` Lei Yang
0 siblings, 1 reply; 2+ messages in thread
From: Vladimir Sementsov-Ogievskiy @ 2025-07-16 7:28 UTC (permalink / raw)
To: qemu-devel, jasowang; +Cc: vsementsov, d-tatianin, leiyang
Theoretically tap_read_packet() may return size less than
s->host_vnet_hdr_len, and next, we'll work with negative size
(in case of !s->using_vnet_hdr). Let's avoid it.
Don't proceed with size == s->host_vnet_hdr_len as well in case
of !s->using_vnet_hdr, it doesn't make sense.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
v2: change "<" -> "<="
net/tap.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/tap.c b/net/tap.c
index 23536c09b46..2a859360193 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -190,6 +190,11 @@ static void tap_send(void *opaque)
break;
}
+ if (s->host_vnet_hdr_len && size <= s->host_vnet_hdr_len) {
+ /* Invalid packet */
+ break;
+ }
+
if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
buf += s->host_vnet_hdr_len;
size -= s->host_vnet_hdr_len;
--
2.48.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH v2] net/tap: drop too small packets
2025-07-16 7:28 [PATCH v2] net/tap: drop too small packets Vladimir Sementsov-Ogievskiy
@ 2025-07-18 8:28 ` Lei Yang
0 siblings, 0 replies; 2+ messages in thread
From: Lei Yang @ 2025-07-18 8:28 UTC (permalink / raw)
To: Vladimir Sementsov-Ogievskiy; +Cc: qemu-devel, jasowang, d-tatianin
[-- Attachment #1: Type: text/plain, Size: 1220 bytes --]
Tested this patch v2 again,everything works fine.
Tested-by: Lei Yang <leiyang@redhat.com>
On Wed, Jul 16, 2025 at 3:29 PM Vladimir Sementsov-Ogievskiy <
vsementsov@yandex-team.ru> wrote:
> Theoretically tap_read_packet() may return size less than
> s->host_vnet_hdr_len, and next, we'll work with negative size
> (in case of !s->using_vnet_hdr). Let's avoid it.
>
> Don't proceed with size == s->host_vnet_hdr_len as well in case
> of !s->using_vnet_hdr, it doesn't make sense.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> ---
>
> v2: change "<" -> "<="
>
> net/tap.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/net/tap.c b/net/tap.c
> index 23536c09b46..2a859360193 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -190,6 +190,11 @@ static void tap_send(void *opaque)
> break;
> }
>
> + if (s->host_vnet_hdr_len && size <= s->host_vnet_hdr_len) {
> + /* Invalid packet */
> + break;
> + }
> +
> if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
> buf += s->host_vnet_hdr_len;
> size -= s->host_vnet_hdr_len;
> --
> 2.48.1
>
>
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