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| author |   Al Viro <viro@zeniv.linux.org.uk> | 2018-05-16 18:19:53 +0300 |
|---|---|---|
| committer |   Miklos Szeredi <mszeredi@redhat.com> | 2018-05-31 11:06:11 +0200 |
| commit | f73cc77c3afffc9a90fad972fe34af52cdb72979 (patch) | |
| tree | 025f4c46514313a2ec0c09f35d652ebdbad7f6b7 /fs/overlayfs | |
| parent | ovl: create helper ovl_create_temp() (diff) | |
| download | linux-dev-f73cc77c3afffc9a90fad972fe34af52cdb72979.tar.xz linux-dev-f73cc77c3afffc9a90fad972fe34af52cdb72979.zip | |
ovl: make ovl_create_real() cope with vfs_mkdir() safely
vfs_mkdir() may succeed and leave the dentry passed to it unhashed and
negative. ovl_create_real() is the last caller breaking when that
happens.
[amir: split re-factoring of ovl_create_temp() to prep patch
add comment about unhashed dir after mkdir
add pr_warn() if mkdir succeeds and lookup fails]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/dir.c | 34 |
1 files changed, 33 insertions, 1 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 1b181292a624..1d59c466d199 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -114,6 +114,37 @@ kill_whiteout: goto out; } +static int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, + umode_t mode) +{ + int err; + struct dentry *d, *dentry = *newdentry; + + err = ovl_do_mkdir(dir, dentry, mode); + if (err) + return err; + + if (likely(!d_unhashed(dentry))) + return 0; + + /* + * vfs_mkdir() may succeed and leave the dentry passed + * to it unhashed and negative. If that happens, try to + * lookup a new hashed and positive dentry. + */ + d = lookup_one_len(dentry->d_name.name, dentry->d_parent, + dentry->d_name.len); + if (IS_ERR(d)) { + pr_warn("overlayfs: failed lookup after mkdir (%pd2, err=%i).\n", + dentry, err); + return PTR_ERR(d); + } + dput(dentry); + *newdentry = d; + + return 0; +} + struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry, struct ovl_cattr *attr) { @@ -135,7 +166,8 @@ struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry, break; case S_IFDIR: - err = ovl_do_mkdir(dir, newdentry, attr->mode); + /* mkdir is special... */ + err = ovl_mkdir_real(dir, &newdentry, attr->mode); break; case S_IFCHR: |