From de7911eaef98b6643d80e4612fe4dcd4528d15b9 Mon Sep 17 00:00:00 2001 From: Ian Jackson Date: Fri, 14 Jun 2013 16:39:38 +0100 Subject: libxc: range checks in xc_dom_p2m_host and _guest These functions take guest pfns and look them up in the p2m. They did no range checking. However, some callers, notably xc_dom_boot.c:setup_hypercall_page want to pass untrusted guest-supplied value(s). It is most convenient to detect this here and return INVALID_MFN. This is part of the fix to a security issue, XSA-55. Signed-off-by: Ian Jackson Cc: Tim Deegan Reviewed-by: George Dunlap Reviewed-by: Andrew Cooper Reviewed-by: Chuck Anderson v6: Check for underflow too (thanks to Andrew Cooper). --- tools/libxc/xc_dom.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/libxc') diff --git a/tools/libxc/xc_dom.h b/tools/libxc/xc_dom.h index 5968e7bc2c..86e23eea9c 100644 --- a/tools/libxc/xc_dom.h +++ b/tools/libxc/xc_dom.h @@ -342,6 +342,8 @@ static inline xen_pfn_t xc_dom_p2m_host(struct xc_dom_image *dom, xen_pfn_t pfn) { if (dom->shadow_enabled) return pfn; + if (pfn < dom->rambase_pfn || pfn >= dom->rambase_pfn + dom->total_pages) + return INVALID_MFN; return dom->p2m_host[pfn - dom->rambase_pfn]; } @@ -350,6 +352,8 @@ static inline xen_pfn_t xc_dom_p2m_guest(struct xc_dom_image *dom, { if (xc_dom_feature_translated(dom)) return pfn; + if (pfn < dom->rambase_pfn || pfn >= dom->rambase_pfn + dom->total_pages) + return INVALID_MFN; return dom->p2m_host[pfn - dom->rambase_pfn]; } -- cgit v1.2.3