hugetlbfs: add NULL check in hugetlb_zero_setup()

If hugetlbfs module_init() fails, hugetlbfs_vfsmount is not initialized and
shmget() with SHM_HUGETLB flag will cause NULL pointer dereference.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 842a4ed4052d..98959b87cdf8 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -747,6 +747,9 @@ struct file *hugetlb_zero_setup(size_t size)
         char buf[16];
         static atomic_t counter;
 
+        if (!hugetlbfs_vfsmount)
+                return ERR_PTR(-ENOENT);
+
         if (!can_do_hugetlb_shm())
                 return ERR_PTR(-EPERM);