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

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Message-ID: <5E054593-8995-46FF-824E-55B18BF53BE2@oracle.com>
Date:   Fri, 12 May 2023 17:31:43 +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 8:09 AM, Chuck Lever III <chuck.lever@...cle.com> wrote:
> 
> 
> 
>> On May 12, 2023, at 7:53 AM, 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.
> 
> 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.

Acked-by: Chuck Lever <chuck.lever@...cle.com <mailto:chuck.lever@...cle.com>>


>> [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>
>> ---
>> v1: https://lore.kernel.org/all/20230510220952.3507366-1-azeemshaikh38@gmail.com/
>> 
>> Changes in v2:
>> - Use __assign_str instead of strscpy.
>> - Added the Fixes tag.
>> 
>> fs/nfsd/trace.h |    6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>> 
>> diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
>> index 4183819ea082..72a906a053dc 100644
>> --- a/fs/nfsd/trace.h
>> +++ b/fs/nfsd/trace.h
>> @@ -1365,19 +1365,19 @@ TRACE_EVENT(nfsd_cb_setup,
>> __field(u32, cl_id)
>> __field(unsigned long, authflavor)
>> __sockaddr(addr, clp->cl_cb_conn.cb_addrlen)
>> - __array(unsigned char, netid, 8)
>> + __string(netid, netid)
>> ),
>> 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));
>> + __assign_str(netid, netid);
>> __entry->authflavor = authflavor;
>> __assign_sockaddr(addr, &clp->cl_cb_conn.cb_addr,
>> clp->cl_cb_conn.cb_addrlen)
>> ),
>> TP_printk("addr=%pISpc client %08x:%08x proto=%s flavor=%s",
>> __get_sockaddr(addr), __entry->cl_boot, __entry->cl_id,
>> - __entry->netid, show_nfsd_authflavor(__entry->authflavor))
>> + __get_str(netid), show_nfsd_authflavor(__entry->authflavor))
>> );
>> 
>> TRACE_EVENT(nfsd_cb_setup_err,
>> -- 
>> 2.40.1.606.ga4b1b128d6-goog
>> 
>> 
> 
> --
> Chuck Lever


--
Chuck Lever