Commit d05f0cdc authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

mm: fix crashes from mbind() merging vmas 



In v2.6.34 commit 9d8cebd4 ("mm: fix mbind vma merge problem")
introduced vma merging to mbind(), but it should have also changed the
convention of passing start vma from queue_pages_range() (formerly
check_range()) to new_vma_page(): vma merging may have already freed
that structure, resulting in BUG at mm/mempolicy.c:1738 and probably
worse crashes.

Fixes: 9d8cebd4 ("mm: fix mbind vma merge problem")
Reported-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Tested-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: <stable@vger.kernel.org>	[2.6.34+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b43ae21b

mm/mempolicy.c

+20 −26
Original line number Diff line number Diff line
@@ -656,19 +656,18 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma, 
 * @nodes and @flags,) it's isolated and queued to the pagelist which is

 * passed via @private.)

 */

static struct vm_area_struct *

static int

queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,

		const nodemask_t *nodes, unsigned long flags, void *private)

{

	int err;

	struct vm_area_struct *first, *vma, *prev;



	int err = 0;

	struct vm_area_struct *vma, *prev;



	first = find_vma(mm, start);

	if (!first)

		return ERR_PTR(-EFAULT);

	vma = find_vma(mm, start);

	if (!vma)

		return -EFAULT;

	prev = NULL;

	for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {

	for (; vma && vma->vm_start < end; vma = vma->vm_next) {

		unsigned long endvma = vma->vm_end;



		if (endvma > end)
@@ -678,9 +677,9 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end, 


		if (!(flags & MPOL_MF_DISCONTIG_OK)) {

			if (!vma->vm_next && vma->vm_end < end)

				return ERR_PTR(-EFAULT);

				return -EFAULT;

			if (prev && prev->vm_end < vma->vm_start)

				return ERR_PTR(-EFAULT);

				return -EFAULT;

		}



		if (flags & MPOL_MF_LAZY) {
@@ -694,15 +693,13 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end, 


			err = queue_pages_pgd_range(vma, start, endvma, nodes,

						flags, private);

			if (err) {

				first = ERR_PTR(err);

			if (err)

				break;

		}

		}

next:

		prev = vma;

	}

	return first;

	return err;

}



/*
@@ -1156,16 +1153,17 @@ out: 


/*

 * Allocate a new page for page migration based on vma policy.

 * Start assuming that page is mapped by vma pointed to by @private.

 * Start by assuming the page is mapped by the same vma as contains @start.

 * Search forward from there, if not.  N.B., this assumes that the

 * list of pages handed to migrate_pages()--which is how we get here--

 * is in virtual address order.

 */

static struct page *new_vma_page(struct page *page, unsigned long private, int **x)

static struct page *new_page(struct page *page, unsigned long start, int **x)

{

	struct vm_area_struct *vma = (struct vm_area_struct *)private;

	struct vm_area_struct *vma;

	unsigned long uninitialized_var(address);



	vma = find_vma(current->mm, start);

	while (vma) {

		address = page_address_in_vma(page, vma);

		if (address != -EFAULT)
@@ -1195,7 +1193,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from, 
	return -ENOSYS;

}



static struct page *new_vma_page(struct page *page, unsigned long private, int **x)

static struct page *new_page(struct page *page, unsigned long start, int **x)

{

	return NULL;

}
@@ -1205,7 +1203,6 @@ static long do_mbind(unsigned long start, unsigned long len, 
		     unsigned short mode, unsigned short mode_flags,

		     nodemask_t *nmask, unsigned long flags)

{

	struct vm_area_struct *vma;

	struct mm_struct *mm = current->mm;

	struct mempolicy *new;

	unsigned long end;
@@ -1271,11 +1268,9 @@ static long do_mbind(unsigned long start, unsigned long len, 
	if (err)

		goto mpol_out;



	vma = queue_pages_range(mm, start, end, nmask,

	err = queue_pages_range(mm, start, end, nmask,

			  flags | MPOL_MF_INVERT, &pagelist);



	err = PTR_ERR(vma);	/* maybe ... */

	if (!IS_ERR(vma))

	if (!err)

		err = mbind_range(mm, start, end, new);



	if (!err) {
@@ -1283,9 +1278,8 @@ static long do_mbind(unsigned long start, unsigned long len, 


		if (!list_empty(&pagelist)) {

			WARN_ON_ONCE(flags & MPOL_MF_LAZY);

			nr_failed = migrate_pages(&pagelist, new_vma_page,

					NULL, (unsigned long)vma,

					MIGRATE_SYNC, MR_MEMPOLICY_MBIND);

			nr_failed = migrate_pages(&pagelist, new_page, NULL,

				start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND);

			if (nr_failed)

				putback_movable_pages(&pagelist);

		}

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