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mprotect: prevent alteration of the PAT bits

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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>
This commit is contained in:
Venki Pallipadi
2008-05-14 16:05:51 -07:00
committed by Linus Torvalds
parent 44c81433e8
commit 1c12c4cf94
2 changed files with 23 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
mm/mprotect.c
+10 -1
View File
@@ -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;