On Wed, Aug 26, 2009 at 04:19:54PM +0200, Milan Holzäpfel wrote:
> Hello,
>
> I compiled xen-tools with GCC-4.3.3 with Stack Smashing Protection
> (SSP) patches by gentoo, and found a small bug in
> tools/python/lowlevel/xc/xc.c. The bug is located in
> pyxc_dom_set_policy_cpuid:
>
> (this is the change which fixes it:)
>
> > @@ -808,7 +808,7 @@
> > static PyObject *pyxc_dom_set_policy_cpuid(XcObject *self,
> > PyObject *args)
> > {
> > - domid_t domid;
> > + int domid;
I would say use uint32_t instead of int.
> >
> > if ( !PyArg_ParseTuple(args, "i", &domid) )
> > return NULL;
>
> domid_t is defined as uint16_t (thus 2 bytes long) in xen header files,
> but the "i" format needs a C "int" type, which is 4 bytes long.
> (<URL:http://docs.python.org/c-api/arg.html>) This error is detected
> by SSP as stack overflow.
What about the two other cases where domid_it is used? The SSP didn't
detect them?
>
> Attached patch fixes the error. Maybe it would better to use "h"
> format instead of the "i" format, which converts the argument to an C
> "short int". Then you would have to change the python wrapper if
> domid_t changes, though.
Yeah, but running more than 64K of guests on one node?
>
> Please apply this patch or the change to the "h" format string (I
> haven't tested it, but I believe it should work just as well).
>
> Regards,
> Milan Holzäpfel
>
>
> --
> Milan Holzaepfel <mail(a)mjh(d)name> <URL:http://mjh.name/>
> pub 4096R/C790FC23 EB8E 5E81 81E3 53A9 9B74 B895 5179 54C0 C790 FC23
> 2009-08-26 Milan Holzaepfel <mail@xxxxxxxx>
>
> As documented on <URL:http://docs.python.org/c-api/arg.html>, the "i"
> format string needs an integer as target.
>
> Error detected by gentoo Stack Smashing Protection for gcc-4.3.3.
>
> --- xen-3.4.1/tools/python/xen/lowlevel/xc/xc.c.orig 2009-08-26
> 13:43:13.000000000 +0000
> +++ xen-3.4.1/tools/python/xen/lowlevel/xc/xc.c 2009-08-26
> 13:43:20.000000000 +0000
> @@ -808,7 +808,7 @@
> static PyObject *pyxc_dom_set_policy_cpuid(XcObject *self,
> PyObject *args)
> {
> - domid_t domid;
> + int domid;
>
> if ( !PyArg_ParseTuple(args, "i", &domid) )
> return NULL;
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