From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from www262.sakura.ne.jp ([202.181.97.72]:59527 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933685AbeEILBd (ORCPT ); Wed, 9 May 2018 07:01:33 -0400 Subject: [PATCH] fuse: don't keep dead fuse_conn at fuse_fill_super(). To: miklos@szeredi.hu References: <0000000000002aeada056b10e833@google.com> <37d2030a-124c-9927-aa48-bb769da792cf@I-love.SAKURA.ne.jp> Cc: syzbot , linux-fsdevel@vger.kernel.org, syzkaller-bugs@googlegroups.com From: Tetsuo Handa Message-ID: Date: Wed, 9 May 2018 20:01:26 +0900 MIME-Version: 1.0 In-Reply-To: <37d2030a-124c-9927-aa48-bb769da792cf@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: >>From 606d54cd24b5b00e7a7e3597aabbe89719defc56 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Tue, 1 May 2018 13:12:14 +0900 Subject: [PATCH] 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 Reported-by: syzbot Fixes: 3b463ae0c6264f70 ("fuse: invalidation reverse calls") Cc: John Muir Cc: Csaba Henk Cc: Anand Avati Cc: Miklos Szeredi --- fs/fuse/inode.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index ef30995..9b37cf8 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1179,6 +1179,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) fuse_dev_free(fud); err_put_conn: fuse_conn_put(fc); + sb->s_fs_info = NULL; err_fput: fput(file); err: -- 1.8.3.1