Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "14 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, page_alloc: do not wake kswapd with zone lock held
  hugetlbfs: revert "use i_mmap_rwsem for more pmd sharing synchronization"
  hugetlbfs: revert "Use i_mmap_rwsem to fix page fault/truncate race"
  mm: page_mapped: don't assume compound page is huge or THP
  mm/memory.c: initialise mmu_notifier_range correctly
  tools/vm/page_owner: use page_owner_sort in the use example
  kasan: fix krealloc handling for tag-based mode
  kasan: make tag based mode work with CONFIG_HARDENED_USERCOPY
  kasan, arm64: use ARCH_SLAB_MINALIGN instead of manual aligning
  mm, memcg: fix reclaim deadlock with writeback
  mm/usercopy.c: no check page span for stack objects
  slab: alien caches must not be initialized if the allocation of the alien cache failed
  fork, memcg: fix cached_stacks case
  zram: idle writeback fixes and cleanup

1 files changed, 5 insertions, 4 deletions

diff --git a/mm/usercopy.c b/mm/usercopy.c
index 852eb4e53f06..14faadcedd06 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -247,7 +247,8 @@ static DEFINE_STATIC_KEY_FALSE_RO(bypass_usercopy_checks);
 /*
  * Validates that the given object is:
  * - not bogus address
- * - known-safe heap or stack object
+ * - fully contained by stack (or stack frame, when available)
+ * - fully within SLAB object (or object whitelist area, when available)
  * - not in kernel text
  */
 void __check_object_size(const void *ptr, unsigned long n, bool to_user)
@@ -262,9 +263,6 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user)
         /* Check for invalid addresses. */
         check_bogus_address((const unsigned long)ptr, n, to_user);
 
-        /* Check for bad heap object. */
-        check_heap_object(ptr, n, to_user);
-
         /* Check for bad stack object. */
         switch (check_stack_object(ptr, n)) {
         case NOT_STACK:
@@ -282,6 +280,9 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user)
                 usercopy_abort("process stack", NULL, to_user, 0, n);
         }
 
+        /* Check for bad heap object. */
+        check_heap_object(ptr, n, to_user);
+
         /* Check for object in kernel to avoid text exposure. */
         check_kernel_text_object((const unsigned long)ptr, n, to_user);
 }