4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> commit 543b8f8662fe6d21f19958b666ab0051af9db21a upstream. 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: 3b463ae0c626 ("fuse: invalidation reverse calls") Cc: John Muir <john@xxxxxxxxx> Cc: Csaba Henk <csaba@xxxxxxxxxxx> Cc: Anand Avati <avati@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.31 Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/fuse/inode.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1184,6 +1184,7 @@ static int fuse_fill_super(struct super_ err_put_conn: fuse_bdi_destroy(fc); fuse_conn_put(fc); + sb->s_fs_info = NULL; err_fput: fput(file); err:
