Commit c7da82b8 authored by Dan Williams's avatar Dan Williams Committed by Linus Torvalds
Browse files

mm: replace pmd_write with pmd_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
   pmd_write is must be referencing user-memory.

Link: http://lkml.kernel.org/r/151043111049.2842.15241454964150083466.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 e7fe7b5c

arch/sparc/mm/gup.c

+1 −1
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, 
	if (!(pmd_val(pmd) & _PAGE_VALID))

		return 0;



	if (write && !pmd_write(pmd))

	if (!pmd_access_permitted(pmd, write))

		return 0;



	refs = 0;

fs/dax.c

+2 −1
Original line number Diff line number Diff line
@@ -627,7 +627,8 @@ static void dax_mapping_entry_mkclean(struct address_space *mapping, 


			if (pfn != pmd_pfn(*pmdp))

				goto unlock_pmd;

			if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp))

			if (!pmd_dirty(*pmdp)

					&& !pmd_access_permitted(*pmdp, WRITE))

				goto unlock_pmd;



			flush_cache_page(vma, address, pfn);

mm/hmm.c

+2 −2
Original line number Diff line number Diff line
@@ -391,11 +391,11 @@ again: 
		if (pmd_protnone(pmd))

			return hmm_vma_walk_clear(start, end, walk);



		if (write_fault && !pmd_write(pmd))

		if (!pmd_access_permitted(pmd, write_fault))

			return hmm_vma_walk_clear(start, end, walk);



		pfn = pmd_pfn(pmd) + pte_index(addr);

		flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0;

		flag |= pmd_access_permitted(pmd, WRITE) ? HMM_PFN_WRITE : 0;

		for (; addr < end; addr += PAGE_SIZE, i++, pfn++)

			pfns[i] = hmm_pfn_t_from_pfn(pfn) | flag;

		return 0;

mm/huge_memory.c

+2 −2
Original line number Diff line number Diff line
@@ -877,7 +877,7 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 
	 */

	WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");



	if (flags & FOLL_WRITE && !pmd_write(*pmd))

	if (!pmd_access_permitted(*pmd, flags & FOLL_WRITE))

		return NULL;



	if (pmd_present(*pmd) && pmd_devmap(*pmd))
@@ -1393,7 +1393,7 @@ out_unlock: 
 */

static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)

{

	return pmd_write(pmd) ||

	return pmd_access_permitted(pmd, WRITE) ||

	       ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));

}

mm/memory.c

+1 −1
Original line number Diff line number Diff line
@@ -4046,7 +4046,7 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, 
			if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))

				return do_huge_pmd_numa_page(&vmf, orig_pmd);



			if (dirty && !pmd_write(orig_pmd)) {

			if (dirty && !pmd_access_permitted(orig_pmd, WRITE)) {

				ret = wp_huge_pmd(&vmf, orig_pmd);

				if (!(ret & VM_FAULT_FALLBACK))

					return ret;

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