On Thu, 2018-06-28 at 12:40 -0400, Steve Dickson wrote: > > On 06/28/2018 12:17 PM, Trond Myklebust wrote: > > On Thu, 2018-06-28 at 11:29 -0400, Steve Dickson wrote: > > > From: Daniel Sands <dnsands@xxxxxxxxxx> > > > > > > The cause is that the xdr_putlong uses a long to store the > > > converted value, then passes it to fwrite as a byte buffer. > > > Only the first 4 bytes are written, which is okay for a LE > > > system after byteswapping, but writes all zeroes on BE systems. > > > > > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1261738 > > > > > > Signed-off-by: Steve Dickson <steved@xxxxxxxxxx> > > > --- > > > src/xdr_stdio.c | 10 +++++----- > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/src/xdr_stdio.c b/src/xdr_stdio.c > > > index 4410262..b415f61 100644 > > > --- a/src/xdr_stdio.c > > > +++ b/src/xdr_stdio.c > > > @@ -103,10 +103,10 @@ xdrstdio_getlong(xdrs, lp) > > > XDR *xdrs; > > > long *lp; > > > { > > > - > > > - if (fread(lp, sizeof(int32_t), 1, (FILE *)xdrs- > > > >x_private) > > > != 1) > > > + u_int32_t mycopy; > > > + if (fread(&mycopy, sizeof(u_int32_t), 1, (FILE *)xdrs- > > > > x_private) != 1) > > > > > > return (FALSE); > > > - *lp = (long)ntohl((u_int32_t)*lp); > > > + *lp = (long)ntohl(mycopy); > > > return (TRUE); > > > } > > > > > > @@ -115,9 +115,9 @@ xdrstdio_putlong(xdrs, lp) > > > XDR *xdrs; > > > const long *lp; > > > { > > > - long mycopy = (long)htonl((u_int32_t)*lp); > > > + u_int32_t mycopy = (u_int32_t)htonl((u_int32_t)*lp); > > > > > > - if (fwrite(&mycopy, sizeof(int32_t), 1, (FILE *)xdrs- > > > > x_private) != 1) > > > > > > + if (fwrite(&mycopy, sizeof(u_int32_t), 1, (FILE *)xdrs- > > > > x_private) != 1) > > > > > > return (FALSE); > > > return (TRUE); > > > } > > > > Hmm... Given that most setups today tend to be 64-bit, shouldn't > > there > > also be bounds checking in the above 'xdrstdio_putlong()' in order > > to > > make it safe? > > > > Something like > > > > if ((long)(u_int32_t)*lp != *lp) return (FALSE); > > > > Sorry... I'm not following this... why is this necessary > and what are you making safe? > A long integer on most 64-bit systems is 64-bit long, but in the code above, you are pushing that value into a 32-bit big-endian integer. So a safe implementation would normally check for whether or not the 64- bit value is getting truncated when it gets cast to u_int32_t, and would throw an error in the case where the long really does not fit into that 32-bit integer. -- Trond Myklebust CTO, Hammerspace Inc 4300 El Camino Real, Suite 105 Los Altos, CA 94022 www.hammer.space ��.n��������+%������w��{.n�����{��w��� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
