From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: syzbot <syzbot+ef054c4d3f64cd7f7cec@syzkaller.appspotmail.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: WARNING in request_end
Date: Tue, 25 Sep 2018 12:18:41 +0300 [thread overview]
Message-ID: <274aafd2-5076-6b14-f55e-360411fb8169@virtuozzo.com> (raw)
In-Reply-To: <CAJfpegu9hZjJOUa7wHAj9KiTpcUuitsqnEMYvQzp6Mha2Yat-g@mail.gmail.com>
On 24.09.2018 17:44, Miklos Szeredi wrote:
> On Mon, Sep 24, 2018 at 2:29 PM, syzbot
> <syzbot+ef054c4d3f64cd7f7cec@syzkaller.appspotmail.com> wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: 6bf4ca7fbc85 Linux 4.19-rc5
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=159149c6400000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=22a62640793a83c9
>> dashboard link: https://syzkaller.appspot.com/bug?extid=ef054c4d3f64cd7f7cec
>> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+ef054c4d3f64cd7f7cec@syzkaller.appspotmail.com
>>
>> WARNING: CPU: 0 PID: 9445 at fs/fuse/dev.c:390 request_end+0x82e/0xaa0
>
> And there we have the bug likely caused by the set_bit(FR_SENT, ...)
> not being inside the fpq->lock-ed region.
>
> So that needs to be fixed anyway, apparently.
I can't confirm, since I haven't found yet the direct way, that set_bit() results
in this stack...
We have one more (unrelated) possible use-after-free here:
cpu0 cpu1
fuse_dev_do_write() fuse_dev_do_write()
req = request_find(fpq, oh.unique) ...
spin_unlock(&fpq->lock) ...
... req = request_find(fpq, oh.unique)
... spin_unlock(&fpq->lock)
queue_interrupt(&fc->iq, req); ...
... ...
... ...
request freed ...
... queue_interrupt(&fc->iq, req); <- use after free
Something like below is needed:
@@ -1875,16 +1877,20 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
/* Is it an interrupt reply? */
if (req->intr_unique == oh.unique) {
+ __fuse_get_request(req);
spin_unlock(&fpq->lock);
err = -EINVAL;
- if (nbytes != sizeof(struct fuse_out_header))
+ if (nbytes != sizeof(struct fuse_out_header)) {
+ fuse_put_request(fc, req);
goto err_finish;
+ }
if (oh.error == -ENOSYS)
fc->no_interrupt = 1;
else if (oh.error == -EAGAIN)
queue_interrupt(&fc->iq, req);
+ fuse_put_request(fc, req);
fuse_copy_finish(cs);
return nbytes;
next prev parent reply other threads:[~2018-09-25 15:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-24 12:29 WARNING in request_end syzbot
2018-09-24 14:44 ` Miklos Szeredi
2018-09-25 9:18 ` Kirill Tkhai [this message]
2018-09-25 9:38 ` Dmitry Vyukov
2018-09-25 9:49 ` Kirill Tkhai
2018-10-08 9:38 ` syzbot
2019-03-23 7:50 ` syzbot
2019-03-23 15:51 ` Eric W. Biederman
2019-03-23 19:48 ` Miklos Szeredi
2019-03-23 20:16 ` syzbot
2019-11-07 13:42 ` syzbot
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