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| author | Miklos Szeredi <mszeredi@redhat.com> | 2018-05-31 12:26:10 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2018-05-31 12:26:10 +0200 |
| commit | 6becdb601bae2a043d7fb9762c4d48699528ea6e (patch) | |
| tree | 7d136a357c374a82bb8e329811d84af96a920a36 | |
| parent | 8a301eb16d99983a4961f884690ec97b92e7dcfe (diff) | |
| download | linux-6becdb601bae2a043d7fb9762c4d48699528ea6e.tar.bz2 | |
fuse: fix control dir setup and teardown
syzbot is reporting NULL pointer dereference at fuse_ctl_remove_conn() [1].
Since fc->ctl_ndents is incremented by fuse_ctl_add_conn() when new_inode()
failed, fuse_ctl_remove_conn() reaches an inode-less dentry and tries to
clear d_inode(dentry)->i_private field.
Fix by only adding the dentry to the array after being fully set up.
When tearing down the control directory, do d_invalidate() on it to get rid
of any mounts that might have been added.
[1] https://syzkaller.appspot.com/bug?id=f396d863067238959c91c0b7cfc10b163638cac6
Reported-by: syzbot <syzbot+32c236387d66c4516827@syzkaller.appspotmail.com>
Fixes: bafa96541b25 ("[PATCH] fuse: add control filesystem")
Cc: <stable@vger.kernel.org> # v2.6.18
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
| -rw-r--r-- | fs/fuse/control.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/fuse/control.c b/fs/fuse/control.c index 78fb7a07c5ca..0b694655d988 100644 --- a/fs/fuse/control.c +++ b/fs/fuse/control.c @@ -211,10 +211,11 @@ static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, if (!dentry) return NULL; - fc->ctl_dentry[fc->ctl_ndents++] = dentry; inode = new_inode(fuse_control_sb); - if (!inode) + if (!inode) { + dput(dentry); return NULL; + } inode->i_ino = get_next_ino(); inode->i_mode = mode; @@ -228,6 +229,9 @@ static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, set_nlink(inode, nlink); inode->i_private = fc; d_add(dentry, inode); + + fc->ctl_dentry[fc->ctl_ndents++] = dentry; + return dentry; } @@ -284,7 +288,10 @@ void fuse_ctl_remove_conn(struct fuse_conn *fc) for (i = fc->ctl_ndents - 1; i >= 0; i--) { struct dentry *dentry = fc->ctl_dentry[i]; d_inode(dentry)->i_private = NULL; - d_drop(dentry); + if (!i) { + /* Get rid of submounts: */ + d_invalidate(dentry); + } dput(dentry); } drop_nlink(d_inode(fuse_control_sb->s_root)); |