linux-kernel - Re: [PATCH net v4] net: skbuff: add usercopy region to skbuff_fclone

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Message-ID: <aUFEk8QPIAIEHcsF@horms.kernel.org>
Date: Tue, 16 Dec 2025 11:37:55 +0000
From: Simon Horman <horms@...nel.org>
To: bestswngs@...il.com
Cc: security@...nel.org, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, xmei5@....edu
Subject: Re: [PATCH net v4] net: skbuff: add usercopy region to
 skbuff_fclone_cache

On Tue, Dec 16, 2025 at 04:44:53PM +0800, bestswngs@...il.com wrote:
> From: Weiming Shi <bestswngs@...il.com>
> 
> skbuff_fclone_cache was created without defining a usercopy region, [1]
> unlike skbuff_head_cache which properly whitelists the cb[] field.  [2]
> This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is enabled
> and the kernel attempts to copy sk_buff.cb data to userspace via
> sock_recv_errqueue() -> put_cmsg().

...

Hi Weiming Shi,

Please slow down.

When posting patches to the Netdev ML please allow 24h to 24h should elapse
between versions. This is to allow time for review. And reduce load on
shared CI infrastructure.

See: https://docs.kernel.org/process/maintainer-netdev.html

Also, I do not believe it is appropriate to involve security@...nel.org
in reports that are made public. As there is nothing left for the security
officers to do.

See:
- https://lore.kernel.org/netdev/CANn89i+3_50FX1RWutvipTMROD3FnK-nBeG4L+br86W85fzRdQ@mail.gmail.com/
- https://www.kernel.org/doc/Documentation/process/security-bugs.rst

Thanks!