Subject: Re: [PATCH net] net: Make copy_safe_from_sockptr() match documentation

From: Jakub Kicinski <[email-masked]>
Date: Wed, 13 Nov 2024 19:29:24 -0800

On Mon, 11 Nov 2024 00:17:34 +0100 Michal Luczaj wrote:
> copy_safe_from_sockptr()
>   return copy_from_sockptr()
>     return copy_from_sockptr_offset()
>       return copy_from_user()
> 
> copy_from_user() does not return an error on fault. Instead, it returns a
> number of bytes that were not copied. Have it handled.
> 
> Fixes: 6309863b31dd ("net: add copy_safe_from_sockptr() helper")
> Signed-off-by: Michal Luczaj <[email-masked]>
> ---
> Patch has a side effect: it un-breaks garbage input handling of
> nfc_llcp_setsockopt() and mISDN's data_sock_setsockopt().

I'll move this to the commit message, it's important.

Are you planning to scan callers of copy_from_sockptr() ?
I looked at 3 callers who save the return value, 2 of them are buggy :S