Merge branch 'master' into next

1 files changed, 21 insertions, 0 deletions

diff --git a/mm/util.c b/mm/util.c
index 834db7be240..f5712e8964b 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -186,6 +186,27 @@ void kzfree(const void *p)
 }
 EXPORT_SYMBOL(kzfree);
 
+int kern_ptr_validate(const void *ptr, unsigned long size)
+{
+	unsigned long addr = (unsigned long)ptr;
+	unsigned long min_addr = PAGE_OFFSET;
+	unsigned long align_mask = sizeof(void *) - 1;
+
+	if (unlikely(addr < min_addr))
+		goto out;
+	if (unlikely(addr > (unsigned long)high_memory - size))
+		goto out;
+	if (unlikely(addr & align_mask))
+		goto out;
+	if (unlikely(!kern_addr_valid(addr)))
+		goto out;
+	if (unlikely(!kern_addr_valid(addr + size - 1)))
+		goto out;
+	return 1;
+out:
+	return 0;
+}
+
 /*
  * strndup_user - duplicate an existing string from user space
  * @s: The string to duplicate