[Xen-devel] [PATCH] Fix ptr calculation when converting from a VA

[jym@xxxxxxxxxx]

From: Jean-Yves Migeon <jym@xxxxxxxxxx>

The ptr calculation shall take the offset into the page into account
when ptr is valid.

Reported regression on NetBSD's port-xen with last known working libxen
being rev 2.9. This corrupts the kernel symbol table when the table is
not loaded on a page boundary.

Issue was tracked down by FastIce and Jeff Rizzo. See also
http://mail-index.netbsd.org/port-xen/2013/10/16/msg008088.html

Signed-off-by: Jean-Yves Migeon <jym@xxxxxxxxxx>
---
 tools/libxc/xc_dom.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/libxc/xc_dom.h b/tools/libxc/xc_dom.h
index a183e62..7099cee 100644
--- a/tools/libxc/xc_dom.h
+++ b/tools/libxc/xc_dom.h
@@ -342,7 +342,7 @@ static inline void *xc_dom_vaddr_to_ptr(struct xc_dom_image 
*dom,
     if ( ptr == NULL )
         return ptr;
     *safe_region_out = (safe_region_count << XC_DOM_PAGE_SHIFT(dom)) - offset;
-    return ptr;
+    return ptr + offset;
 }
 
 static inline xen_pfn_t xc_dom_p2m_host(struct xc_dom_image *dom, xen_pfn_t 
pfn)
-- 
1.8.1.5


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