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Code

binfmt_misc: switch to locked_recursive_removal()

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... fixing a mount leak, strictly speaking.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2025-03-08 19:54:09 -05:00
parent 8c0e092e38
commit eacb58fdca
1 changed files with 3 additions and 41 deletions
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44
fs/binfmt_misc.c
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@ -674,44 +674,6 @@ static void bm_evict_inode(struct inode *inode)
} }
} }
/**
* unlink_binfmt_dentry - remove the dentry for the binary type handler
* @dentry: dentry associated with the binary type handler
*
* Do the actual filesystem work to remove a dentry for a registered binary
* type handler. Since binfmt_misc only allows simple files to be created
* directly under the root dentry of the filesystem we ensure that we are
* indeed passed a dentry directly beneath the root dentry, that the inode
* associated with the root dentry is locked, and that it is a regular file we
* are asked to remove.
*/
static void unlink_binfmt_dentry(struct dentry *dentry)
{
struct dentry *parent = dentry->d_parent;
struct inode *inode, *parent_inode;
/* All entries are immediate descendants of the root dentry. */
if (WARN_ON_ONCE(dentry->d_sb->s_root != parent))
return;
/* We only expect to be called on regular files. */
inode = d_inode(dentry);
if (WARN_ON_ONCE(!S_ISREG(inode->i_mode)))
return;
/* The parent inode must be locked. */
parent_inode = d_inode(parent);
if (WARN_ON_ONCE(!inode_is_locked(parent_inode)))
return;
if (simple_positive(dentry)) {
dget(dentry);
simple_unlink(parent_inode, dentry);
d_delete(dentry);
dput(dentry);
}
}
/** /**
* remove_binfmt_handler - remove a binary type handler * remove_binfmt_handler - remove a binary type handler
* @misc: handle to binfmt_misc instance * @misc: handle to binfmt_misc instance
@ -729,7 +691,7 @@ static void remove_binfmt_handler(struct binfmt_misc *misc, Node *e)
write_lock(&misc->entries_lock); write_lock(&misc->entries_lock);
list_del_init(&e->list); list_del_init(&e->list);
write_unlock(&misc->entries_lock); write_unlock(&misc->entries_lock);
unlink_binfmt_dentry(e->dentry); locked_recursive_removal(e->dentry, NULL);
} }
/* /<entry> */ /* /<entry> */
@ -772,7 +734,7 @@ static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
case 3: case 3:
/* Delete this handler. */ /* Delete this handler. */
inode = d_inode(inode->i_sb->s_root); inode = d_inode(inode->i_sb->s_root);
inode_lock(inode); inode_lock_nested(inode, I_MUTEX_PARENT);
/* /*
* In order to add new element or remove elements from the list * In order to add new element or remove elements from the list
@ -922,7 +884,7 @@ static ssize_t bm_status_write(struct file *file, const char __user *buffer,
case 3: case 3:
/* Delete all handlers. */ /* Delete all handlers. */
inode = d_inode(file_inode(file)->i_sb->s_root); inode = d_inode(file_inode(file)->i_sb->s_root);
inode_lock(inode); inode_lock_nested(inode, I_MUTEX_PARENT);
/* /*
* In order to add new element or remove elements from the list * In order to add new element or remove elements from the list