From 82cb4113b6ace16de192021de20f6cbd991e478f Mon Sep 17 00:00:00 2001 From: Ian Jackson Date: Fri, 14 Jun 2013 16:39:38 +0100 Subject: 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 --- tools/libxc/xc_dom_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'tools/libxc') 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, -- cgit v1.2.3