[PATCH] mkfs.f2fs: fix to calculate left space of checkpoint page correctly

[Chao Yu <chao2.yu@samsung.com>]

We reserved one segment for NAT region at least, so when formatting
fs, calculated maximum size of left space in CP page should be:
CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1 - 64 (size of
reserved NAT bitmap).

Fix the incorrect calculated size to avoid potential overflow bug here.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
 mkfs/f2fs_format.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
index c4b17de..a2f33f9 100644
--- a/mkfs/f2fs_format.c
+++ b/mkfs/f2fs_format.c
@@ -220,7 +220,7 @@ static int f2fs_prepare_super_block(void)
 	 * When sit is too large, we should expand cp area. It requires more pages for cp.
 	 */
 	if (max_sit_bitmap_size >
-			(CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 65)) {
+			(CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1 - 64)) {
 		max_nat_bitmap_size = CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1;
 		set_sb(cp_payload, F2FS_BLK_ALIGN(max_sit_bitmap_size));
 	} else {
-- 
2.6.3



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