From: Ian Jackson Date: Fri, 14 Jun 2013 15:39:38 +0000 (+0100) Subject: libxc: Better range check in xc_dom_alloc_segment X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~6719 X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=82cb4113b6ace16de192021de20f6cbd991e478f;p=xen.git libxc: Better range check in xc_dom_alloc_segment If seg->pfn is too large, the arithmetic in the range check might overflow, defeating the range check. This is part of the fix to a security issue, XSA-55. Signed-off-by: Ian Jackson Reviewed-by: Andrew Cooper --- diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c index 5f188c1321..3df71714aa 100644 --- a/tools/libxc/xc_dom_core.c +++ b/tools/libxc/xc_dom_core.c @@ -511,7 +511,8 @@ int xc_dom_alloc_segment(struct xc_dom_image *dom, seg->vstart = start; seg->pfn = (seg->vstart - dom->parms.virt_base) / page_size; - if ( pages > dom->total_pages || /* double test avoids overflow probs */ + if ( pages > dom->total_pages || /* multiple test avoids overflow probs */ + seg->pfn > dom->total_pages || pages > dom->total_pages - seg->pfn) { xc_dom_panic(dom->xch, XC_OUT_OF_MEMORY,