[PATCH] f2fs: fix to verify tpage before releasing in f2fs_free_dic()

[Chao Yu]

In below error path, tpages[i] could be NULL, fix to check it before
releasing it.
- f2fs_read_multi_pages
 - f2fs_alloc_dic
  - f2fs_free_dic

Fixes: 61fbae2b2b12 ("f2fs: fix to avoid NULL pointer dereference")
Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
 fs/f2fs/compress.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 1d692108dbbb..8d025fe6d60c 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1339,6 +1339,8 @@ void f2fs_free_dic(struct decompress_io_ctx *dic)
 		for (i = 0; i < dic->cluster_size; i++) {
 			if (dic->rpages[i])
 				continue;
+			if (!dic->tpages[i])
+				continue;
 			unlock_page(dic->tpages[i]);
 			put_page(dic->tpages[i]);
 		}
-- 
2.18.0.rc1