linux-kernel - Re: [PATCH] NFSD: Replace all non-returning strlcpy with strscpy

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Message-ID: <72239648-C807-4CDD-8DA7-18440C83384E@oracle.com>
Date:   Thu, 11 May 2023 14:47:54 +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>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] NFSD: Replace all non-returning strlcpy with strscpy

Hello Azeem -

> On May 10, 2023, at 3:09 PM, Azeem Shaikh <azeemshaikh38@...il.com> wrote:
> 
> 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 with strscpy().
> No return values were used, so direct replacement is safe.

Actually netid should use the __string() and __assign_str()
macros rather than open-coding a string copy, I think.


> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
> 

I suggest adding:

Fixes: 3c92fba557c6 ("NFSD: Enhance the nfsd_cb_setup tracepoint")

> Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
> ---
> fs/nfsd/trace.h |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
> index 4183819ea082..9b32cda54808 100644
> --- a/fs/nfsd/trace.h
> +++ b/fs/nfsd/trace.h
> @@ -1370,7 +1370,7 @@ TRACE_EVENT(nfsd_cb_setup,
> TP_fast_assign(
> __entry->cl_boot = clp->cl_clientid.cl_boot;
> __entry->cl_id = clp->cl_clientid.cl_id;
> - strlcpy(__entry->netid, netid, sizeof(__entry->netid));
> + strscpy(__entry->netid, netid, sizeof(__entry->netid));
> __entry->authflavor = authflavor;
> __assign_sockaddr(addr, &clp->cl_cb_conn.cb_addr,
>  clp->cl_cb_conn.cb_addrlen)
> 

--
Chuck Lever