f2fs: sanity check for total valid node blocks

commit 8a29c12 upstream.

This patch enhances sanity check for SIT entries.

syzbot hit the following crash on upstream commit
83beed7 (Fri Apr 20 17:56:32 2018 +0000)
Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal
syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=bf9253040425feb155ad

syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=5692130282438656
Raw console output: https://syzkaller.appspot.com/x/log.txt?id=5095924598571008
Kernel config: https://syzkaller.appspot.com/x/.config?id=1808800213120130118
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bf9253040425feb155ad@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for details.
If you forward the report, please keep this part and the footer.

F2FS-fs (loop0): invalid crc value
F2FS-fs (loop0): Try to recover 1th superblock, ret: 0
F2FS-fs (loop0): Mounted with checkpoint version = d
F2FS-fs (loop0): Bitmap was wrongly cleared, blk:9740
------------[ cut here ]------------
kernel BUG at fs/f2fs/segment.c:1884!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 4508 Comm: syz-executor0 Not tainted 4.17.0-rc1+ #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:update_sit_entry+0x1215/0x1590 fs/f2fs/segment.c:1882
RSP: 0018:ffff8801af526708 EFLAGS: 00010282
RAX: ffffed0035ea4cc0 RBX: ffff8801ad454f90 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff82eeb87e RDI: ffffed0035ea4cb6
RBP: ffff8801af526760 R08: ffff8801ad4a2480 R09: ffffed003b5e4f90
R10: ffffed003b5e4f90 R11: ffff8801daf27c87 R12: ffff8801adb8d380
R13: 0000000000000001 R14: 0000000000000008 R15: 00000000ffffffff
FS:  00000000014af940(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f06bc223000 CR3: 00000001adb02000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 allocate_data_block+0x66f/0x2050 fs/f2fs/segment.c:2663
 do_write_page+0x105/0x1b0 fs/f2fs/segment.c:2727
 write_node_page+0x129/0x350 fs/f2fs/segment.c:2770
 __write_node_page+0x7da/0x1370 fs/f2fs/node.c:1398
 sync_node_pages+0x18cf/0x1eb0 fs/f2fs/node.c:1652
 block_operations+0x429/0xa60 fs/f2fs/checkpoint.c:1088
 write_checkpoint+0x3ba/0x5380 fs/f2fs/checkpoint.c:1405
 f2fs_sync_fs+0x2fb/0x6a0 fs/f2fs/super.c:1077
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem+0x265/0x310 fs/sync.c:67
 generic_shutdown_super+0xd7/0x520 fs/super.c:429
 kill_block_super+0xa4/0x100 fs/super.c:1191
 kill_f2fs_super+0x9f/0xd0 fs/f2fs/super.c:3030
 deactivate_locked_super+0x97/0x100 fs/super.c:316
 deactivate_super+0x188/0x1b0 fs/super.c:347
 cleanup_mnt+0xbf/0x160 fs/namespace.c:1174
 __cleanup_mnt+0x16/0x20 fs/namespace.c:1181
 task_work_run+0x1e4/0x290 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x2bd/0x310 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457d97
RSP: 002b:00007ffd46f9c8e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000457d97
RDX: 00000000014b09a3 RSI: 0000000000000002 RDI: 00007ffd46f9da50
RBP: 00007ffd46f9da50 R08: 0000000000000000 R09: 0000000000000009
R10: 0000000000000005 R11: 0000000000000246 R12: 00000000014b0940
R13: 0000000000000000 R14: 0000000000000002 R15: 000000000000658e
RIP: update_sit_entry+0x1215/0x1590 fs/f2fs/segment.c:1882 RSP: ffff8801af526708
---[ end trace f498328bb02610a2 ]---

Reported-and-tested-by: syzbot+bf9253040425feb155ad@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+7d6d31d3bc702f566ce3@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+0a725420475916460f12@syzkaller.appspotmail.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/f2fs/segment.c

@@ -3600,6 +3600,7 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 	unsigned int i, start, end;
 	unsigned int readed, start_blk = 0;
 	int err = 0;
+	block_t total_node_blocks = 0;
 
 	do {
 		readed = ra_meta_pages(sbi, start_blk, BIO_MAX_PAGES,
@@ -3622,6 +3623,8 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 			if (err)
 				return err;
 			seg_info_from_raw_sit(se, &sit);
+			if (IS_NODESEG(se->type))
+				total_node_blocks += se->valid_blocks;
 
 			/* build discard map only one time */
 			if (f2fs_discard_en(sbi)) {
@@ -3663,11 +3666,15 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 		sit = sit_in_journal(journal, i);
 
 		old_valid_blocks = se->valid_blocks;
+		if (IS_NODESEG(se->type))
+			total_node_blocks -= old_valid_blocks;
 
 		err = check_block_count(sbi, start, &sit);
 		if (err)
 			break;
 		seg_info_from_raw_sit(se, &sit);
+		if (IS_NODESEG(se->type))
+			total_node_blocks += se->valid_blocks;
 
 		if (f2fs_discard_en(sbi)) {
 			if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
@@ -3686,6 +3693,15 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 				se->valid_blocks - old_valid_blocks;
 	}
 	up_read(&curseg->journal_rwsem);
+
+	if (!err && total_node_blocks != valid_node_count(sbi)) {
+		f2fs_msg(sbi->sb, KERN_ERR,
+			"SIT is corrupted node# %u vs %u",
+			total_node_blocks, valid_node_count(sbi));
+		set_sbi_flag(sbi, SBI_NEED_FSCK);
+		err = -EINVAL;
+	}
+
 	return err;
 }