linux-kernel - Re: [PATCH net v2] usbnet: limit max_mtu based on device's hard

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Message-Id: 
 <176896500760.707355.7611917521322998807.git-patchwork-notify@kernel.org>
Date: Wed, 21 Jan 2026 03:10:07 +0000
From: patchwork-bot+netdevbpf@...nel.org
To: Laurent Vivier <lvivier@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org, oneukum@...e.com,
 kuba@...nel.org, netdev@...r.kernel.org, sbrivio@...hat.com
Subject: Re: [PATCH net v2] usbnet: limit max_mtu based on device's hard_mtu

Hello:

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

On Mon, 19 Jan 2026 08:55:18 +0100 you wrote:
> The usbnet driver initializes net->max_mtu to ETH_MAX_MTU before calling
> the device's bind() callback. When the bind() callback sets
> dev->hard_mtu based the device's actual capability (from CDC Ethernet's
> wMaxSegmentSize descriptor), max_mtu is never updated to reflect this
> hardware limitation).
> 
> This allows userspace (DHCP or IPv6 RA) to configure MTU larger than the
> device can handle, leading to silent packet drops when the backend sends
> packet exceeding the device's buffer size.
> 
> [...]

Here is the summary with links:
  - [net,v2] usbnet: limit max_mtu based on device's hard_mtu
    https://git.kernel.org/netdev/net/c/c7159e960f14

You are awesome, thank you!
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