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authorVenki Pallipadi <venkatesh.pallipadi@intel.com>2008-05-15 03:05:51 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-15 06:11:15 +0400
commit1c12c4cf9411eb130b245fa8d0fbbaf989477c7b (patch)
treef61d58e955b3159007ef77513c1c4f1ed2c9ec23 /mm
parent44c81433e8b05dbc85985d939046f10f95901184 (diff)
downloadlinux-1c12c4cf9411eb130b245fa8d0fbbaf989477c7b.tar.xz
mprotect: prevent alteration of the PAT bits
There is a defect in mprotect, which lets the user change the page cache type bits by-passing the kernel reserve_memtype and free_memtype wrappers. Fix the problem by not letting mprotect change the PAT bits. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mprotect.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 4de546899dc1..a5bf31c27375 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -26,6 +26,13 @@
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
+#ifndef pgprot_modify
+static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
+{
+ return newprot;
+}
+#endif
+
static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
@@ -192,7 +199,9 @@ success:
* held in write mode.
*/
vma->vm_flags = newflags;
- vma->vm_page_prot = vm_get_page_prot(newflags);
+ vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
+ vm_get_page_prot(newflags));
+
if (vma_wants_writenotify(vma)) {
vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
dirty_accountable = 1;