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authorVenki Pallipadi <venkatesh.pallipadi@intel.com>2008-05-14 19:05:51 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-14 22:11:15 -0400
commit1c12c4cf9411eb130b245fa8d0fbbaf989477c7b (patch)
treef61d58e955b3159007ef77513c1c4f1ed2c9ec23 /mm/mprotect.c
parent44c81433e8b05dbc85985d939046f10f95901184 (diff)
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/mprotect.c')
-rw-r--r--mm/mprotect.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 4de546899dc..a5bf31c2737 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -26,6 +26,13 @@
26#include <asm/cacheflush.h> 26#include <asm/cacheflush.h>
27#include <asm/tlbflush.h> 27#include <asm/tlbflush.h>
28 28
29#ifndef pgprot_modify
30static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
31{
32 return newprot;
33}
34#endif
35
29static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, 36static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
30 unsigned long addr, unsigned long end, pgprot_t newprot, 37 unsigned long addr, unsigned long end, pgprot_t newprot,
31 int dirty_accountable) 38 int dirty_accountable)
@@ -192,7 +199,9 @@ success:
192 * held in write mode. 199 * held in write mode.
193 */ 200 */
194 vma->vm_flags = newflags; 201 vma->vm_flags = newflags;
195 vma->vm_page_prot = vm_get_page_prot(newflags); 202 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
203 vm_get_page_prot(newflags));
204
196 if (vma_wants_writenotify(vma)) { 205 if (vma_wants_writenotify(vma)) {
197 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED); 206 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
198 dirty_accountable = 1; 207 dirty_accountable = 1;