On Fri, 2018-06-29 at 16:02 -0400, Chuck Lever wrote: > > On Jun 29, 2018, at 3:48 PM, Trond Myklebust <trondmy@hammerspace.c > > om> wrote: > > > > On Fri, 2018-06-29 at 15:33 -0400, Chuck Lever wrote: > > > > On Jun 29, 2018, at 3:29 PM, Trond Myklebust <trondmy@hammerspa > > > > ce.c > > > > om> wrote: > > > > > > > > On Fri, 2018-06-29 at 14:42 -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> > > > > > --- > > > > > v2: Added bounds checking > > > > > Changed from unsigned to signed > > > > > > > > > > src/xdr_stdio.c | 14 +++++++++++--- > > > > > 1 file changed, 11 insertions(+), 3 deletions(-) > > > > > > > > > > diff --git a/src/xdr_stdio.c b/src/xdr_stdio.c > > > > > index 4410262..b902acd 100644 > > > > > --- a/src/xdr_stdio.c > > > > > +++ b/src/xdr_stdio.c > > > > > @@ -103,10 +103,12 @@ xdrstdio_getlong(xdrs, lp) > > > > > XDR *xdrs; > > > > > long *lp; > > > > > { > > > > > + int32_t mycopy; > > > > > > > > > > - if (fread(lp, sizeof(int32_t), 1, (FILE *)xdrs- > > > > > > x_private) > > > > > > > > > > != 1) > > > > > + if (fread(&mycopy, sizeof(int32_t), 1, (FILE *)xdrs- > > > > > > x_private) != 1) > > > > > > > > > > return (FALSE); > > > > > - *lp = (long)ntohl((u_int32_t)*lp); > > > > > + > > > > > + *lp = (long)ntohl(mycopy); > > > > > return (TRUE); > > > > > } > > > > > > > > > > @@ -115,8 +117,14 @@ xdrstdio_putlong(xdrs, lp) > > > > > XDR *xdrs; > > > > > const long *lp; > > > > > { > > > > > - long mycopy = (long)htonl((u_int32_t)*lp); > > > > > + int32_t mycopy; > > > > > + > > > > > +#if defined(_LP64) > > > > > + if ((*lp > INT32_MAX) || (*lp < INT32_MIN)) > > > > > + return (FALSE); > > > > > > > > The will work just fine if your cast is: > > > > int a; > > > > > > > > lp = (long)a; > > > > > > > > ...but it won't do the right thing for > > > > > > > > unsigned int b = UINT32_MAX; > > > > > > > > lp = (long)b; /* set lp to UINT32_MAX */ > > > > > > mycopy is an int32_t now. Does that help? > > > > Not really. 'mycopy' isn't involved in the check above, and *lp == > > UINT32_MAX should in either case get cast to the same 32-bit bit > > pattern whether mycopy is an int32_t or a u_int32_t. > > It's when you try to cast back from 'mycopy' to a long type that > > the > > two can end up differing (an int32_t might get sign extended). > > AFAICT we are casting *lp to an int32_t in this function. mycopy > is not being cast to a long here. > > Do you mean xdrstdio_GETlong needs further protection? Could be, > there is a cast of an int32_t to a long there. > > I agree that we should vet xdrstdio_getlong and xdrstdio_putlong for > sign-extension issues very carefully. > The worry for xdrstdio_putlong() should be how we handle the truncation when going from (long)-> big endian (int32_t/u_int32_t). We don't want to silently lose information. AFAICS, when casting from a 'long' type, whether 'mycopy' is signed or unsigned doesn't really matter when considering what ends up getting encoded, as long as it is of size 32-bits. The exception would be if sizeof(long) < 4, but libtirpc is broken for that case anyway... > > > > Since there us no dedicated xdrstdio_putulong() to use for > > > > unsigned > > > > integers, we need the check to work for both cases. > > > > For that reason, I think the above check either has to be: > > > > > > > > if (*lp == (long)((u_int32_t)*lp)) > > > > return (FALSE); > > > > > > > > ...or something uglier like > > > > > > > > if (*lp > UINT32_MAX || *lp < INT32_MIN) > > > > return (FALSE); > > > > > > > > > +#endif > > > > > > > > > > + mycopy = (int32_t)htonl((int32_t)*lp); > > > > > if (fwrite(&mycopy, sizeof(int32_t), 1, (FILE *)xdrs- > > > > > > x_private) != 1) > > > > > > > > > > return (FALSE); > > > > > return (TRUE); > > > > > > > > -- > > > > Trond Myklebust > > > > CTO, Hammerspace Inc > > > > 4300 El Camino Real, Suite 105 > > > > Los Altos, CA 94022 > > > > www.hammer.space > > > > > > > > N‹§ēæėrļ›yúčšØbēXŽķĮ§vØ^–)Þš{.nĮ+‰·ĨŠ{ąû"žØ^n‡rĄöĶzËëh™ĻčÚ& > > > > Ēø Ū > > > > GŦéhŪ(階ŠÝĒj"úķm§ĸïęäzđÞ–ŠāþfĢĒ·hšˆ§~ˆm > > > > > > -- > > > Chuck Lever > > > > > > > > > > > > > -- > > Trond Myklebust > > Linux NFS client maintainer, Hammerspace > > trond.myklebust@xxxxxxxxxxxxxxx > > -- > Chuck Lever > > > -- 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
