[patch 04/14] remap_file_pages protection support: disallow mprotect() on manyprots mappings

[blaisorblade]

From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@xxxxxxxx>

For now we (I and Hugh) have found no agreement on which behavior to implement
here. So, at least as a stop-gap, return an error here.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@xxxxxxxx>
Index: linux-2.6.git/mm/mprotect.c
===================================================================
--- linux-2.6.git.orig/mm/mprotect.c
+++ linux-2.6.git/mm/mprotect.c
@@ -217,6 +217,13 @@ sys_mprotect(unsigned long start, size_t
 	error = -ENOMEM;
 	if (!vma)
 		goto out;
+
+	/* If a need is felt, an appropriate behaviour may be implemented for
+	 * this case. We haven't agreed yet on which behavior is appropriate. */
+	error = -EACCES;
+	if (vma->vm_flags & VM_MANYPROTS)
+		goto out;
+
 	if (unlikely(grows & PROT_GROWSDOWN)) {
 		if (vma->vm_start >= end)
 			goto out;

--
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade
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