[RFC PATCH 2/6] [ARM] mm/mmap.c: Check length of unmapped area before allowing MAP_FIXED

[Liam Howlett]

arch_get_unmapped_area() could potentially allow a larger than possible
length when using the MAP_FIXED flag.  The bound check should come
before the check for MAP_FIXED.

Fixes: 4fbe66759b2a ([ARM] Fix shared mmap()ings for ARM VIPT caches.)
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
 arch/arm/mm/mmap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index a0f8a0ca0788..cb135556ce36 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -36,6 +36,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	int aliasing = cache_is_vipt_aliasing();
 	struct vm_unmapped_area_info info;
 
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
 	/*
 	 * We only need to do colour alignment if either the I or D
 	 * caches alias.
@@ -53,9 +56,6 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		return addr;
 	}
 
-	if (len > TASK_SIZE)
-		return -ENOMEM;
-
 	if (addr) {
 		if (do_align)
 			addr = COLOUR_ALIGN(addr, pgoff);
-- 
2.30.2