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

[Azeem Shaikh]

On Fri, May 12, 2023 at 10:38 AM Chuck Lever III <chuck.lever@xxxxxxxxxx> wrote:
>
>
>
> > On May 12, 2023, at 7:30 AM, Azeem Shaikh <azeemshaikh38@xxxxxxxxx> wrote:
> >
> > Thanks Chuck and Kees for the review.
> >
> >>> Actually netid should use the __string() and __assign_str()
> >>> macros rather than open-coding a string copy, I think.
> >
> > Do you mean something like this?
> >
> > 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))
> > );
>
> Yes. I don't remember why I chose to open-code the string
> handling in here.
>
> I agree with Kees, also: __assign_str() needs to handle
> the memory accesses properly, and I had assumed it did
> that already. My bad. That IMO should be handled as a
> separate patch.

Thanks I'll send out a patch with the __assign_str replacement for now.
I'll wait for Kees and Steve to respond on how to fix the memory
access in __assign_str.

> >>> Fixes: 3c92fba557c6 ("NFSD: Enhance the nfsd_cb_setup tracepoint")
> >
> > Ack.
>
> I agree that it's not a high priority backport. However,
> I expect those who want to use trace points on KASAN-
> enabled stable kernels might prefer to have the
> __assign_str fix in place, along with this one.
>
> So, I'm good with including Fixes: or leaving it off. Up
> to you!
>

Will include it :)