[PATCH] udp: using datalen to cap max gso segments

[PATCH] udp: using datalen to cap max gso segments

[Jianguo Wu]

From: Jianguo Wu <wujianguo@chinatelecom.cn>

The max number of UDP gso segments is intended to cap to UDP_MAX_SEGMENTS,
this is checked in udp_send_skb():

    if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
        kfree_skb(skb);
        return -EINVAL;
    }

skb->len contains network and transport header len here, we should use
only data len instead.

Fixes: bec1f6f69736 ("udp: generate gso with UDP_SEGMENT")
Signed-off-by: Jianguo Wu <wujianguo@chinatelecom.cn>
---
 net/ipv4/udp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 8bcecdd6aeda..23b05e28490b 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -916,7 +916,7 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
 			kfree_skb(skb);
 			return -EINVAL;
 		}
-		if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
+		if (datalen > cork->gso_size * UDP_MAX_SEGMENTS) {
 			kfree_skb(skb);
 			return -EINVAL;
 		}
-- 
1.8.3.1

Re: [PATCH] udp: using datalen to cap max gso segments

[Willem de Bruijn]

On Wed, Dec 8, 2021 at 5:03 AM Jianguo Wu <wujianguo106@163.com> wrote:
>
> From: Jianguo Wu <wujianguo@chinatelecom.cn>
>
> The max number of UDP gso segments is intended to cap to UDP_MAX_SEGMENTS,
> this is checked in udp_send_skb():
>
>     if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
>         kfree_skb(skb);
>         return -EINVAL;
>     }
>
> skb->len contains network and transport header len here, we should use
> only data len instead.
>
> Fixes: bec1f6f69736 ("udp: generate gso with UDP_SEGMENT")
> Signed-off-by: Jianguo Wu <wujianguo@chinatelecom.cn>

Reviewed-by: Willem de Bruijn <willemb@google.com>

Thanks Jianguo

Re: [PATCH] udp: using datalen to cap max gso segments

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 8 Dec 2021 18:03:33 +0800 you wrote:
> From: Jianguo Wu <wujianguo@chinatelecom.cn>
> 
> The max number of UDP gso segments is intended to cap to UDP_MAX_SEGMENTS,
> this is checked in udp_send_skb():
> 
>     if (skb->len > cork->gso_size * UDP_MAX_SEGMENTS) {
>         kfree_skb(skb);
>         return -EINVAL;
>     }
> 
> [...]

Here is the summary with links:
  - udp: using datalen to cap max gso segments
    https://git.kernel.org/netdev/net/c/158390e45612

You are awesome, thank you!
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