linux-kernel - Re: [PATCH] fuse: Fix use-after-free in fuse_dev_do

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Message-ID: <CAJfpegugvGFMYHCCTewcFe67XwVgRQrXnnucGZg=W+uqnj93=Q@mail.gmail.com>
Date:   Mon, 1 Oct 2018 11:25:42 +0200
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>
Cc:     syzbot <syzbot+4e975615ca01f2277bdd@...kaller.appspotmail.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fuse: Fix use-after-free in fuse_dev_do_read()

On Tue, Sep 25, 2018 at 11:28 AM, Kirill Tkhai <ktkhai@...tuozzo.com> wrote:
> We may pick freed req in this way:
>
> [cpu0]                                              [cpu1]
> fuse_dev_do_read()                                  fuse_dev_do_write()
>    list_move_tail(&req->list, &fpq->processing);      ...
>    spin_unlock(&fpq->lock);                           ...
>    ...                                                request_end(fc, req);
>    ...                                                  fuse_put_request(fc, req);
>    if (test_bit(FR_INTERRUPTED, &req->flags))
>          queue_interrupt(fiq, req);
>
> Fix that by keeping req alive till we finish all manipulations.
>
> Reported-by: syzbot+4e975615ca01f2277bdd@...kaller.appspotmail.com
> Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>

Applied.

Thanks,
Miklos