>From 606d54cd24b5b00e7a7e3597aabbe89719defc56 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> 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 <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Reported-by: syzbot <syzbot+ec3986119086fe4eec97@xxxxxxxxxxxxxxxxxxxxxxxxx> Fixes: 3b463ae0c6264f70 ("fuse: invalidation reverse calls") Cc: John Muir <john@xxxxxxxxx> Cc: Csaba Henk <csaba@xxxxxxxxxxx> Cc: Anand Avati <avati@xxxxxxxxxx> Cc: Miklos Szeredi <mszeredi@xxxxxxxxxx> --- 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
