linux-kernel - [PATCH V2] fs/ntfs3: cancle set bad inode after removing name fails

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Message-ID: <tencent_BCCDAC7BEE6CFC2DD96CF095ACE9F2EDDE0A@qq.com>
Date: Wed, 18 Jun 2025 15:31:57 +0800
From: Edward Adam Davis <eadavis@...com>
To: eadavis@...com
Cc: almaz.alexandrovich@...agon-software.com,
	brauner@...nel.org,
	jack@...e.cz,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	ntfs3@...ts.linux.dev,
	syzbot+1aa90f0eb1fc3e77d969@...kaller.appspotmail.com,
	syzkaller-bugs@...glegroups.com,
	viro@...iv.linux.org.uk
Subject: [PATCH V2] fs/ntfs3: cancle set bad inode after removing name fails

The reproducer uses a file0 on a ntfs3 file system with a corrupted i_link.
When renaming, the file0's inode is marked as a bad inode because the file
name cannot be deleted.

The underlying bug is that make_bad_inode() is called on a live inode.
In some cases it's "icache lookup finds a normal inode, d_splice_alias()
is called to attach it to dentry, while another thread decides to call
make_bad_inode() on it - that would evict it from icache, but we'd already
found it there earlier".
In some it's outright "we have an inode attached to dentry - that's how we
got it in the first place; let's call make_bad_inode() on it just for shits
and giggles".

Fixes: 78ab59fee07f ("fs/ntfs3: Rework file operations")
Reported-by: syzbot+1aa90f0eb1fc3e77d969@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1aa90f0eb1fc3e77d969
Signed-off-by: Edward Adam Davis <eadavis@...com>
---
V1 -> V2: fix it by removing set bad inode

 fs/ntfs3/frecord.c |  7 +++----
 fs/ntfs3/namei.c   | 10 +++-------
 fs/ntfs3/ntfs_fs.h |  3 +--
 3 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c
index 756e1306fe6c..7afbb4418eb2 100644
--- a/fs/ntfs3/frecord.c
+++ b/fs/ntfs3/frecord.c
@@ -3003,8 +3003,7 @@ int ni_add_name(struct ntfs_inode *dir_ni, struct ntfs_inode *ni,
  * ni_rename - Remove one name and insert new name.
  */
 int ni_rename(struct ntfs_inode *dir_ni, struct ntfs_inode *new_dir_ni,
-	      struct ntfs_inode *ni, struct NTFS_DE *de, struct NTFS_DE *new_de,
-	      bool *is_bad)
+	      struct ntfs_inode *ni, struct NTFS_DE *de, struct NTFS_DE *new_de)
 {
 	int err;
 	struct NTFS_DE *de2 = NULL;
@@ -3027,8 +3026,8 @@ int ni_rename(struct ntfs_inode *dir_ni, struct ntfs_inode *new_dir_ni,
 	err = ni_add_name(new_dir_ni, ni, new_de);
 	if (!err) {
 		err = ni_remove_name(dir_ni, ni, de, &de2, &undo);
-		if (err && ni_remove_name(new_dir_ni, ni, new_de, &de2, &undo))
-			*is_bad = true;
+		WARN_ON(err && ni_remove_name(new_dir_ni, ni, new_de, &de2,
+			&undo));
 	}
 
 	/*
diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index b807744fc6a9..0db7ca3b64ea 100644
--- a/fs/ntfs3/namei.c
+++ b/fs/ntfs3/namei.c
@@ -244,7 +244,7 @@ static int ntfs_rename(struct mnt_idmap *idmap, struct inode *dir,
 	struct ntfs_inode *ni = ntfs_i(inode);
 	struct inode *new_inode = d_inode(new_dentry);
 	struct NTFS_DE *de, *new_de;
-	bool is_same, is_bad;
+	bool is_same;
 	/*
 	 * de		- memory of PATH_MAX bytes:
 	 * [0-1024)	- original name (dentry->d_name)
@@ -313,12 +313,8 @@ static int ntfs_rename(struct mnt_idmap *idmap, struct inode *dir,
 	if (dir_ni != new_dir_ni)
 		ni_lock_dir2(new_dir_ni);
 
-	is_bad = false;
-	err = ni_rename(dir_ni, new_dir_ni, ni, de, new_de, &is_bad);
-	if (is_bad) {
-		/* Restore after failed rename failed too. */
-		_ntfs_bad_inode(inode);
-	} else if (!err) {
+	err = ni_rename(dir_ni, new_dir_ni, ni, de, new_de);
+	if (!err) {
 		simple_rename_timestamp(dir, dentry, new_dir, new_dentry);
 		mark_inode_dirty(inode);
 		mark_inode_dirty(dir);
diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
index 36b8052660d5..f54635df18fa 100644
--- a/fs/ntfs3/ntfs_fs.h
+++ b/fs/ntfs3/ntfs_fs.h
@@ -577,8 +577,7 @@ int ni_add_name(struct ntfs_inode *dir_ni, struct ntfs_inode *ni,
 		struct NTFS_DE *de);
 
 int ni_rename(struct ntfs_inode *dir_ni, struct ntfs_inode *new_dir_ni,
-	      struct ntfs_inode *ni, struct NTFS_DE *de, struct NTFS_DE *new_de,
-	      bool *is_bad);
+	      struct ntfs_inode *ni, struct NTFS_DE *de, struct NTFS_DE *new_de);
 
 bool ni_is_dirty(struct inode *inode);
 
-- 
2.43.0