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fsnotify: fix fsnotify hooks in pseudo filesystems 

commit 29044dae2e upstream.

Commit 49246466a9 ("fsnotify: move fsnotify_nameremove() hook out of
d_delete()") moved the fsnotify delete hook before d_delete() so fsnotify
will have access to a positive dentry.

This allowed a race where opening the deleted file via cached dentry
is now possible after receiving the IN_DELETE event.

To fix the regression in pseudo filesystems, convert d_delete() calls
to d_drop() (see commit 46c46f8df9 ("devpts_pty_kill(): don't bother
with d_delete()") and move the fsnotify hook after d_drop().

Add a missing fsnotify_unlink() hook in nfsdfs that was found during
the audit of fsnotify hooks in pseudo filesystems.

Note that the fsnotify hooks in simple_recursive_removal() follow
d_invalidate(), so they require no change.

Link: https://lore.kernel.org/r/20220120215305.282577-2-amir73il@gmail.com
Reported-by: Ivan Delalande <colona@arista.com>
Link: https://lore.kernel.org/linux-fsdevel/YeNyzoDM5hP5LtGW@visor/
Fixes: 49246466a9 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Amir Goldstein 2022-01-20 23:53:05 +02:00 committed by Greg Kroah-Hartman
parent 1614bd844e
commit 5463cfd833
4 changed files with 9 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fs/configfs/dir.c
View File

@ -1805,8 +1805,8 @@ void configfs_unregister_group(struct config_group *group)
configfs_detach_group(&group->cg_item);
d_inode(dentry)->i_flags |= S_DEAD;
dont_mount(dentry);
d_drop(dentry);
fsnotify_rmdir(d_inode(parent), dentry);
d_delete(dentry);
inode_unlock(d_inode(parent));
dput(dentry);
@ -1947,10 +1947,10 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
configfs_detach_group(&group->cg_item);
d_inode(dentry)->i_flags |= S_DEAD;
dont_mount(dentry);
fsnotify_rmdir(d_inode(root), dentry);
inode_unlock(d_inode(dentry));
d_delete(dentry);
d_drop(dentry);
fsnotify_rmdir(d_inode(root), dentry);
inode_unlock(d_inode(root));

2
fs/devpts/inode.c
View File

@ -621,8 +621,8 @@ void devpts_pty_kill(struct dentry *dentry)
dentry->d_fsdata = NULL;
drop_nlink(dentry->d_inode);
fsnotify_unlink(d_inode(dentry->d_parent), dentry);
d_drop(dentry);
fsnotify_unlink(d_inode(dentry->d_parent), dentry);
dput(dentry); /* d_alloc_name() in devpts_pty_new() */
}

5
fs/nfsd/nfsctl.c
View File

@ -1247,7 +1247,8 @@ static void nfsdfs_remove_file(struct inode *dir, struct dentry *dentry)
clear_ncl(d_inode(dentry));
dget(dentry);
ret = simple_unlink(dir, dentry);
d_delete(dentry);
d_drop(dentry);
fsnotify_unlink(dir, dentry);
dput(dentry);
WARN_ON_ONCE(ret);
}
@ -1336,8 +1337,8 @@ void nfsd_client_rmdir(struct dentry *dentry)
dget(dentry);
ret = simple_rmdir(dir, dentry);
WARN_ON_ONCE(ret);
d_drop(dentry);
fsnotify_rmdir(dir, dentry);
d_delete(dentry);
dput(dentry);
inode_unlock(dir);
}

4
net/sunrpc/rpc_pipe.c
View File

@ -599,9 +599,9 @@ static int __rpc_rmdir(struct inode *dir, struct dentry *dentry)
dget(dentry);
ret = simple_rmdir(dir, dentry);
d_drop(dentry);
if (!ret)
fsnotify_rmdir(dir, dentry);
d_delete(dentry);
dput(dentry);
return ret;
}
@ -612,9 +612,9 @@ static int __rpc_unlink(struct inode *dir, struct dentry *dentry)
dget(dentry);
ret = simple_unlink(dir, dentry);
d_drop(dentry);
if (!ret)
fsnotify_unlink(dir, dentry);
d_delete(dentry);
dput(dentry);
return ret;
}