fuse: don't keep dead fuse_conn at fuse_fill_super().
authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tue, 1 May 2018 04:12:14 +0000 (13:12 +0900)
committerMiklos Szeredi <mszeredi@redhat.com>
Thu, 31 May 2018 10:26:11 +0000 (12:26 +0200)
commit543b8f8662fe6d21f19958b666ab0051af9db21a
tree4e880da0dfdcdcaeb34e992749529e29f061c631
parent6becdb601bae2a043d7fb9762c4d48699528ea6e
fuse: don't keep dead fuse_conn at fuse_fill_super().

syzbot is reporting use-after-free at fuse_kill_sb_blk() [1].
Since sb->s_fs_info field is not cleared after fc was released by
fuse_conn_put() when initialization failed, fuse_kill_sb_blk() finds
already released fc and tries to hold the lock. Fix this by clearing
sb->s_fs_info field after calling fuse_conn_put().

[1] https://syzkaller.appspot.com/bug?id=a07a680ed0a9290585ca424546860464dd9658db

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+ec3986119086fe4eec97@syzkaller.appspotmail.com>
Fixes: 3b463ae0c626 ("fuse: invalidation reverse calls")
Cc: John Muir <john@jmuir.com>
Cc: Csaba Henk <csaba@gluster.com>
Cc: Anand Avati <avati@redhat.com>
Cc: <stable@vger.kernel.org> # v2.6.31
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
fs/fuse/inode.c