diff options
| author | Mike Christie <mchristi@redhat.com> | 2018-07-15 18:16:17 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-26 08:36:38 +0200 |
| commit | 5e790d7b09662e2f53db17d6f8e2a3db31d6ec2a (patch) | |
| tree | d411f49403e274e89f22e70ecd0e6fdef617aeec /fs/configfs | |
| parent | bffe67b9fe9d887420ebd08822c898730b13ba95 (diff) | |
configfs: fix registered group removal
[ Upstream commit cc57c07343bd071cdf1915a91a24ab7d40c9b590 ]
This patch fixes a bug where configfs_register_group had added
a group in a tree, and userspace has done a rmdir on a dir somewhere
above that group and we hit a kernel crash. The problem is configfs_rmdir
will detach everything under it and unlink groups on the default_groups
list. It will not unlink groups added with configfs_register_group so when
configfs_unregister_group is called to drop its references to the group/items
we crash when we try to access the freed dentrys.
The patch just adds a check for if a rmdir has been done above
us and if so just does the unlink part of unregistration.
Sorry if you are getting this multiple times. I thouhgt I sent
this to some of you and lkml, but I do not see it.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/configfs')
| -rw-r--r-- | fs/configfs/dir.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 56fb26127fef..d2a1a79fa324 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -1777,6 +1777,16 @@ void configfs_unregister_group(struct config_group *group) struct dentry *dentry = group->cg_item.ci_dentry; struct dentry *parent = group->cg_item.ci_parent->ci_dentry; + mutex_lock(&subsys->su_mutex); + if (!group->cg_item.ci_parent->ci_group) { + /* + * The parent has already been unlinked and detached + * due to a rmdir. + */ + goto unlink_group; + } + mutex_unlock(&subsys->su_mutex); + inode_lock_nested(d_inode(parent), I_MUTEX_PARENT); spin_lock(&configfs_dirent_lock); configfs_detach_prep(dentry, NULL); @@ -1791,6 +1801,7 @@ void configfs_unregister_group(struct config_group *group) dput(dentry); mutex_lock(&subsys->su_mutex); +unlink_group: unlink_group(group); mutex_unlock(&subsys->su_mutex); } |