1 files changed, 41 insertions, 2 deletions
diff --git a/mm/util.c b/mm/util.c
index 54e5e761a9a9..ac63e5ca8b21 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -343,6 +343,38 @@ unsigned long randomize_stack_top(unsigned long stack_top)
 #endif
 }
 
+/**
+ * randomize_page - Generate a random, page aligned address
+ * @start:	The smallest acceptable address the caller will take.
+ * @range:	The size of the area, starting at @start, within which the
+ *		random address must fall.
+ *
+ * If @start + @range would overflow, @range is capped.
+ *
+ * NOTE: Historical use of randomize_range, which this replaces, presumed that
+ * @start was already page aligned.  We now align it regardless.
+ *
+ * Return: A page aligned address within [start, start + range).  On error,
+ * @start is returned.
+ */
+unsigned long randomize_page(unsigned long start, unsigned long range)
+{
+	if (!PAGE_ALIGNED(start)) {
+		range -= PAGE_ALIGN(start) - start;
+		start = PAGE_ALIGN(start);
+	}
+
+	if (start > ULONG_MAX - range)
+		range = ULONG_MAX - start;
+
+	range >>= PAGE_SHIFT;
+
+	if (range == 0)
+		return start;
+
+	return start + (get_random_long() % range << PAGE_SHIFT);
+}
+
 #ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
 unsigned long arch_randomize_brk(struct mm_struct *mm)
 {
@@ -592,8 +624,15 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
 		return NULL;
 	}
 
-	return __vmalloc_node(size, 1, flags, node,
-			__builtin_return_address(0));
+	/*
+	 * kvmalloc() can always use VM_ALLOW_HUGE_VMAP,
+	 * since the callers already cannot assume anything
+	 * about the resulting pointer, and cannot play
+	 * protection games.
+	 */
+	return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
+			flags, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
+			node, __builtin_return_address(0));
 }
 EXPORT_SYMBOL(kvmalloc_node);