--- /dev/null
+From d05f0cdcbe6388723f1900c549b4850360545201 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Mon, 23 Jun 2014 13:22:07 -0700
+Subject: mm: fix crashes from mbind() merging vmas
+
+From: Hugh Dickins <hughd@google.com>
+
+commit d05f0cdcbe6388723f1900c549b4850360545201 upstream.
+
+In v2.6.34 commit 9d8cebd4bcd7 ("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: 9d8cebd4bcd7 ("mm: fix mbind vma merge problem")
+Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
+Tested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Christoph Lameter <cl@linux.com>
+Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
+Cc: Minchan Kim <minchan.kim@gmail.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ mm/mempolicy.c | 53 ++++++++++++++++++++++++-----------------------------
+ 1 file changed, 24 insertions(+), 29 deletions(-)
+
+--- a/mm/mempolicy.c
++++ b/mm/mempolicy.c
+@@ -566,24 +566,24 @@ static inline int check_pgd_range(struct
+ * If pagelist != NULL then isolate pages from the LRU and
+ * put them on the pagelist.
+ */
+-static struct vm_area_struct *
++static int
+ check_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) {
+ 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 (!is_vm_hugetlb_page(vma) &&
+ ((flags & MPOL_MF_STRICT) ||
+@@ -597,14 +597,12 @@ check_range(struct mm_struct *mm, unsign
+ start = vma->vm_start;
+ err = check_pgd_range(vma, start, endvma, nodes,
+ flags, private);
+- if (err) {
+- first = ERR_PTR(err);
++ if (err)
+ break;
+- }
+ }
+ prev = vma;
+ }
+- return first;
++ return err;
+ }
+
+ /*
+@@ -945,16 +943,15 @@ static int migrate_to_node(struct mm_str
+ {
+ nodemask_t nmask;
+ LIST_HEAD(pagelist);
+- int err = 0;
+- struct vm_area_struct *vma;
++ int err;
+
+ nodes_clear(nmask);
+ node_set(source, nmask);
+
+- vma = check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
++ err = check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
+ flags | MPOL_MF_DISCONTIG_OK, &pagelist);
+- if (IS_ERR(vma))
+- return PTR_ERR(vma);
++ if (err)
++ return err;
+
+ if (!list_empty(&pagelist)) {
+ err = migrate_pages(&pagelist, new_node_page, dest,
+@@ -1058,16 +1055,17 @@ 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)
+@@ -1093,7 +1091,7 @@ int do_migrate_pages(struct mm_struct *m
+ 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;
+ }
+@@ -1103,7 +1101,6 @@ static long do_mbind(unsigned long start
+ 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;
+@@ -1167,19 +1164,17 @@ static long do_mbind(unsigned long start
+ if (err)
+ goto mpol_out;
+
+- vma = check_range(mm, start, end, nmask,
++ err = check_range(mm, start, end, nmask,
+ flags | MPOL_MF_INVERT, &pagelist);
+
+- err = PTR_ERR(vma);
+- if (!IS_ERR(vma)) {
++ if (!err) {
+ int nr_failed = 0;
+
+ err = mbind_range(mm, start, end, new);
+
+ if (!list_empty(&pagelist)) {
+- nr_failed = migrate_pages(&pagelist, new_vma_page,
+- (unsigned long)vma,
+- false, true);
++ nr_failed = migrate_pages(&pagelist, new_page,
++ start, false, true);
+ if (nr_failed)
+ putback_lru_pages(&pagelist);
+ }
projects / thirdparty / kernel / stable-queue.git / commitdiff
