>From 9f41081f8bd6762a6f629e5e23e6d07a62bba69c Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Date: Sat, 28 Apr 2018 11:24:09 +0900 Subject: [PATCH] fuse: don't keep inode-less dentry at fuse_ctl_add_dentry(). 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 this by calling dput() rather than incrementing fc->ctl_ndents when new_inode() failed. [1] https://syzkaller.appspot.com/bug?id=f396d863067238959c91c0b7cfc10b163638cac6 Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Reported-by: syzbot <syzbot+32c236387d66c4516827@xxxxxxxxxxxxxxxxxxxxxxxxx> Fixes: bafa96541b250a70 ("fuse: add control filesystem") Cc: Miklos Szeredi <miklos@xxxxxxxxxx> --- fs/fuse/control.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/fuse/control.c b/fs/fuse/control.c index b9ea99c..a651f8e 100644 --- a/fs/fuse/control.c +++ b/fs/fuse/control.c @@ -211,10 +211,12 @@ 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; + } + fc->ctl_dentry[fc->ctl_ndents++] = dentry; inode->i_ino = get_next_ino(); inode->i_mode = mode; -- 1.8.3.1
