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Commit 5c9d2d5c authored by Dan Williams's avatar Dan Williams Committed by Linus Torvalds
Browse files

mm: replace pte_write with pte_access_permitted in fault + gup paths 

The 'access_permitted' helper is used in the gup-fast path and goes
beyond the simple _PAGE_RW check to also:

 - validate that the mapping is writable from a protection keys
   standpoint

 - validate that the pte has _PAGE_USER set since all fault paths where
   pte_write is must be referencing user-memory.

Link: http://lkml.kernel.org/r/151043111604.2842.8051684481794973100.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c7da82b8

mm/gup.c

+1 −1
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address, 
 */

static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)

{

	return pte_write(pte) ||

	return pte_access_permitted(pte, WRITE) ||

		((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));

}

mm/hmm.c

+2 −2
Original line number Diff line number Diff line
@@ -456,11 +456,11 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, 
			continue;

		}



		if (write_fault && !pte_write(pte))

		if (!pte_access_permitted(pte, write_fault))

			goto fault;



		pfns[i] = hmm_pfn_t_from_pfn(pte_pfn(pte)) | flag;

		pfns[i] |= pte_write(pte) ? HMM_PFN_WRITE : 0;

		pfns[i] |= pte_access_permitted(pte, WRITE) ? HMM_PFN_WRITE : 0;

		continue;



fault:

mm/memory.c

+2 −2
Original line number Diff line number Diff line
@@ -3948,7 +3948,7 @@ static int handle_pte_fault(struct vm_fault *vmf) 
	if (unlikely(!pte_same(*vmf->pte, entry)))

		goto unlock;

	if (vmf->flags & FAULT_FLAG_WRITE) {

		if (!pte_write(entry))

		if (!pte_access_permitted(entry, WRITE))

			return do_wp_page(vmf);

		entry = pte_mkdirty(entry);

	}
@@ -4336,7 +4336,7 @@ int follow_phys(struct vm_area_struct *vma, 
		goto out;

	pte = *ptep;



	if ((flags & FOLL_WRITE) && !pte_write(pte))

	if (!pte_access_permitted(pte, flags & FOLL_WRITE))

		goto unlock;



	*prot = pgprot_val(pte_pgprot(pte));