(#for-bcachefs, on top of #work.namei)
>From bbe6a7c899e7f265c5a6d01a178336a405e98ed6 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue, 14 Nov 2023 18:52:42 -0500
Subject: [PATCH 2/2] bch2_ioctl_subvolume_destroy(): fix locking
make it use user_path_locked_at() to get the normal directory protection
for modifications, as well as stable ->d_parent and ->d_name in victim
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
fs/bcachefs/fs-ioctl.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/fs/bcachefs/fs-ioctl.c b/fs/bcachefs/fs-ioctl.c
index 5a39bcb597a3..c5ab5a2dc9be 100644
--- a/fs/bcachefs/fs-ioctl.c
+++ b/fs/bcachefs/fs-ioctl.c
@@ -453,33 +453,36 @@ static long bch2_ioctl_subvolume_create(struct bch_fs *c, struct file *filp,
static long bch2_ioctl_subvolume_destroy(struct bch_fs *c, struct file *filp,
struct bch_ioctl_subvolume arg)
{
+ const char __user *name = (void __user *)(unsigned long)arg.dst_ptr;
struct path path;
struct inode *dir;
+ struct dentry *victim;
int ret = 0;
if (arg.flags)
return -EINVAL;
- ret = user_path_at(arg.dirfd,
- (const char __user *)(unsigned long)arg.dst_ptr,
- LOOKUP_FOLLOW, &path);
- if (ret)
- return ret;
+ victim = user_path_locked_at(arg.dirfd, name, &path);
+ if (IS_ERR(victim))
+ return PTR_ERR(victim);
- if (path.dentry->d_sb->s_fs_info != c) {
+ if (victim->d_sb->s_fs_info != c) {
ret = -EXDEV;
goto err;
}
-
- dir = path.dentry->d_parent->d_inode;
-
- ret = __bch2_unlink(dir, path.dentry, true);
- if (ret)
+ if (!d_is_positive(victim)) {
+ ret = -ENOENT;
goto err;
-
- fsnotify_rmdir(dir, path.dentry);
- d_delete(path.dentry);
+ }
+ dir = d_inode(path.dentry);
+ ret = __bch2_unlink(dir, victim, true);
+ if (!ret) {
+ fsnotify_rmdir(dir, victim);
+ d_delete(victim);
+ }
+ inode_unlock(dir);
err:
+ dput(victim);
path_put(&path);
return ret;
}
--
2.39.2
