f2fs: fix to do sanity check for sb/cp fields correctly

This patch fixes below problems of sb/cp sanity check:
- in sanity_check_raw_superi(), it missed to consider log header
blocks while cp_payload check.
- in f2fs_sanity_check_ckpt(), it missed to check nat_bits_blocks.

Cc: <stable@kernel.org>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -3264,11 +3264,13 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
 		return -EFSCORRUPTED;
 	}
 
-	if (le32_to_cpu(raw_super->cp_payload) >
-				(blocks_per_seg - F2FS_CP_PACKS)) {
-		f2fs_info(sbi, "Insane cp_payload (%u > %u)",
+	if (le32_to_cpu(raw_super->cp_payload) >=
+				(blocks_per_seg - F2FS_CP_PACKS -
+				NR_CURSEG_PERSIST_TYPE)) {
+		f2fs_info(sbi, "Insane cp_payload (%u >= %u)",
 			  le32_to_cpu(raw_super->cp_payload),
-			  blocks_per_seg - F2FS_CP_PACKS);
+			  blocks_per_seg - F2FS_CP_PACKS -
+			  NR_CURSEG_PERSIST_TYPE);
 		return -EFSCORRUPTED;
 	}
 
@@ -3304,6 +3306,7 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
 	unsigned int cp_pack_start_sum, cp_payload;
 	block_t user_block_count, valid_user_blocks;
 	block_t avail_node_count, valid_node_count;
+	unsigned int nat_blocks, nat_bits_bytes, nat_bits_blocks;
 	int i, j;
 
 	total = le32_to_cpu(raw_super->segment_count);
@@ -3434,6 +3437,17 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
 		return 1;
 	}
 
+	nat_blocks = nat_segs << log_blocks_per_seg;
+	nat_bits_bytes = nat_blocks / BITS_PER_BYTE;
+	nat_bits_blocks = F2FS_BLK_ALIGN((nat_bits_bytes << 1) + 8);
+	if (__is_set_ckpt_flags(ckpt, CP_NAT_BITS_FLAG) &&
+		(cp_payload + F2FS_CP_PACKS +
+		NR_CURSEG_PERSIST_TYPE + nat_bits_blocks >= blocks_per_seg)) {
+		f2fs_warn(sbi, "Insane cp_payload: %u, nat_bits_blocks: %u)",
+			  cp_payload, nat_bits_blocks);
+		return -EFSCORRUPTED;
+	}
+
 	if (unlikely(f2fs_cp_error(sbi))) {
 		f2fs_err(sbi, "A bug case: need to run fsck");
 		return 1;