[POWERPC] Fix size check for hugetlbfs

My "slices" address space management code that was added in the 2.6.22
implementation of get_unmapped_area() doesn't properly check that the
size is a multiple of the requested page size.  This allows userland to
create VMAs that aren't a multiple of the huge page size with hugetlbfs
(since hugetlbfs entirely relies on get_unmapped_area() to do that
checking) which leads to a kernel BUG() when such areas are torn down.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index f833dba2a028..d5fd3909d13a 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -405,6 +405,8 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
 
         if (len > mm->task_size)
                 return -ENOMEM;
+        if (len & ((1ul << pshift) - 1))
+                return -EINVAL;
         if (fixed && (addr & ((1ul << pshift) - 1)))
                 return -EINVAL;
         if (fixed && addr > (mm->task_size - len))