linux-hardening - Re: [PATCH v2] NFSD: Remove all occurences of strlcpy

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Date:   Sat, 13 May 2023 02:22:06 +0000
From:   Chuck Lever III <chuck.lever@...cle.com>
To:     Azeem Shaikh <azeemshaikh38@...il.com>
CC:     Jeff Layton <jlayton@...nel.org>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] NFSD: Remove all occurences of strlcpy



> On May 12, 2023, at 1:34 PM, Azeem Shaikh <azeemshaikh38@...il.com> wrote:
> 
> Resending as plain text.
> 
>>>> strlcpy() reads the entire source buffer first.
>>>> This read may exceed the destination size limit.
>>>> This is both inefficient and can lead to linear read
>>>> overflows if a source string is not NUL-terminated [1].
>>>> In an effort to remove strlcpy() completely [2], replace
>>>> strlcpy here.
>>> 
>>> Let's update the patch description. This change is really
>>> a clean up -- it doesn't address the memory issues you
>>> originally described.
>> 
>> Unless, of course, you intend to apply this patch /after/
>> a patch that fixes __assign_str(). In that case, no change
>> to the patch description is needed.
> 
> No, I plan to land this patch before attempting to fix __assign_str itself.
> Let me know if the below description looks good to you and I'll send
> over a v3 patch:
> 
> [PATCH v3] NFSD: Remove open coding of string copy
> 
> Instead of open coding a __dynamic_array(), use the __string() and
> __assign_str()
> helper macros that exist for this kind of use case.
> 
> Part of an effort to remove deprecated strlcpy() [1] completely from the
> kernel[2].
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
> 
> Fixes: 3c92fba557c6 ("NFSD: Enhance the nfsd_cb_setup tracepoint")
> Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>

This looks good to me. So you'd like me to take this through
the nfsd tree, possibly for 6.4-rc ?


--
Chuck Lever