[PATCH v2] f2fs: initialize ino_entry_info before checkpoint load

[Deepanshu Kartikey]

When f2fs_get_valid_checkpoint() fails during mount (e.g. due to an
invalid checkpoint CRC on a malformed image), f2fs_fill_super() takes
an error path that eventually calls iput() on the root inode. This
invokes f2fs_drop_inode() -> f2fs_exist_written_data(), which acquires
sbi->im[]->ino_lock. However, f2fs_init_ino_entry_info() has not run
yet at this point, so the spinlock is uninitialized and lockdep
complains:

  F2FS-fs (loop0): invalid crc value
  F2FS-fs (loop0): Failed to get valid F2FS checkpoint
  INFO: trying to register non-static key.
  The code is fine but needs lockdep annotation, or maybe
  you didn't initialize this object before use?
  ...
   f2fs_exist_written_data+0x53/0x90 fs/f2fs/checkpoint.c:787
   f2fs_drop_inode+0xda/0xbf0 fs/f2fs/super.c:1852
   iput+0x651/0xe80 fs/inode.c:2009
   f2fs_fill_super+0x6047/0x7850 fs/f2fs/super.c:5461

Move f2fs_init_ino_entry_info() to before f2fs_get_valid_checkpoint()
so that sbi->im[] is always fully initialized before any error path
can trigger iput() -> f2fs_drop_inode(). The init function only
depends on raw superblock fields (BLKS_PER_SEG, F2FS_CP_PACKS,
NR_CURSEG_PERSIST_TYPE, __cp_payload), which are populated well
before checkpoint load, so the move is safe.

Fixes: 3063c80776e3 ("f2fs: another way to set large folio by remembering inode number")
Cc: stable@xxxxxxxxxx
Reported-by: syzbot+eec8f2693d71386bd600@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=eec8f2693d71386bd600
Tested-by: syzbot+eec8f2693d71386bd600@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Deepanshu Kartikey <kartikey406@xxxxxxxxx>
---
Changes in v2:
 - Add Fixes: tag (suggested by Chao Yu)
 - Add Cc: stable@xxxxxxxxxx
---
 fs/f2fs/super.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index c6afdbd6e1cd..6a231a5b0d62 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -5140,6 +5140,13 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
 		goto free_page_array_cache;
 	}
 
+	/*
+	 * Initialize ino entry info early so f2fs_drop_inode ->
+	 * f2fs_exist_written_data can safely take im->ino_lock if mount
+	 * fails after this point and triggers iput on cleanup.
+	 */
+	f2fs_init_ino_entry_info(sbi);
+
 	err = f2fs_get_valid_checkpoint(sbi);
 	if (err) {
 		f2fs_err(sbi, "Failed to get valid F2FS checkpoint");
@@ -5184,8 +5191,6 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	f2fs_init_extent_cache_info(sbi);
 
-	f2fs_init_ino_entry_info(sbi);
-
 	f2fs_init_fsync_node_info(sbi);
 
 	/* setup checkpoint request control and start checkpoint issue thread */
-- 
2.43.0