[PATCH] vmalloc: Fix NULL pointer dereference in is_vm_area_hugepages()

[Hui Zhu]

From: Hui Zhu <zhuhui@xxxxxxxxxx>

find_vm_area() can return NULL if the given address is not a valid
vmalloc area. Check the return value before dereferencing it to avoid
a kernel crash.

Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>
---
 include/linux/vmalloc.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 3b02c0c6b371..d87dc7f77f4e 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -265,7 +265,9 @@ static inline bool is_vm_area_hugepages(const void *addr)
 	 * allocated in the vmalloc layer.
 	 */
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
-	return find_vm_area(addr)->page_order > 0;
+	struct vm_struct *area = find_vm_area(addr);
+
+	return area && area->page_order > 0;
 #else
 	return false;
 #endif
-- 
2.43.0