debuggers.hg
changeset 20934:02107eca8fb7
libxc: Check full range of pfns for xc_dom_pfn_to_ptr
Previously, passing a valid pfn but an overly large count to
xc_dom_pfn_to_ptr, and functions which call it, would run off the end
of the pfn array giving undefined behaviour.
It is tempting to change this check to an assert, as no callers should
be providing invalid parameters here. But this is probably best not
done while frozen for 4.0.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Previously, passing a valid pfn but an overly large count to
xc_dom_pfn_to_ptr, and functions which call it, would run off the end
of the pfn array giving undefined behaviour.
It is tempting to change this check to an assert, as no callers should
be providing invalid parameters here. But this is probably best not
done while frozen for 4.0.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
| author | Keir Fraser <keir.fraser@citrix.com> |
|---|---|
| date | Wed Feb 03 09:45:40 2010 +0000 (2010-02-03) |
| parents | b48b5e688470 |
| children | 7a10f8513b3f |
| files | tools/libxc/xc_dom_core.c |
line diff
1.1 --- a/tools/libxc/xc_dom_core.c Wed Feb 03 09:45:25 2010 +0000 1.2 +++ b/tools/libxc/xc_dom_core.c Wed Feb 03 09:45:40 2010 +0000 1.3 @@ -288,7 +288,9 @@ void *xc_dom_pfn_to_ptr(struct xc_dom_im 1.4 unsigned int page_shift = XC_DOM_PAGE_SHIFT(dom); 1.5 char *mode = "unset"; 1.6 1.7 - if ( pfn > dom->total_pages ) 1.8 + if ( pfn > dom->total_pages || /* multiple checks to avoid overflows */ 1.9 + count > dom->total_pages || 1.10 + pfn > dom->total_pages - count ) 1.11 { 1.12 xc_dom_printf("%s: pfn out of range (0x%" PRIpfn " > 0x%" PRIpfn ")\n", 1.13 __FUNCTION__, pfn, dom->total_pages);