From: Christian Brauner <[email protected]>
To: Al Viro <[email protected]>
Cc: Jens Axboe <[email protected]>,
syzbot <[email protected]>,
[email protected], [email protected],
[email protected], [email protected]
Subject: Re: [syzbot] WARNING in mntput_no_expire (2)
Date: Sun, 4 Apr 2021 19:05:13 +0200 [thread overview]
Message-ID: <20210404170513.mfl5liccdaxjnpls@wittgenstein> (raw)
In-Reply-To: <[email protected]>
On Sun, Apr 04, 2021 at 04:44:06PM +0000, Al Viro wrote:
> On Sun, Apr 04, 2021 at 06:40:40PM +0200, Christian Brauner wrote:
>
> > > Very interesting. What happens if you call loop() twice? And now I wonder
> > > whether it's root or cwd, actually... Hmm...
> > >
> > > How about this:
> > > fd = open("/proc/self/mountinfo", 0);
> > > mkdir("./newroot/foo", 0777);
> > > mount("./newroot/foo", "./newroot/foo", 0, MS_BIND, NULL);
> > > chroot("./newroot");
> > > chdir("/foo");
> > > while (1) {
> > > static char buf[4096];
> > > int n = read(fd, buf, 4096);
> > > if (n <= 0)
> > > break;
> > > write(1, buf, n);
> > > }
> > > close(fd);
> > > drop_caps();
> > > loop();
> > > as the end of namespace_sandbox_proc(), instead of
> > > chroot("./newroot");
> > > chdir("/");
> > > drop_caps();
> > > loop();
> > > sequence we have there?
> >
> > Uhum, well then we oops properly with a null-deref.
>
> Cute... Could you dump namei.o (ideally - with namei.s) from your build
> someplace public?
Yeah, I have at least namei.o
https://drive.google.com/file/d/1AvO1St0YltIrA86DXjp1Xg3ojtS9owGh/view?usp=sharing
Christian
next prev parent reply other threads:[~2021-04-04 17:05 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <[email protected]>
2021-04-01 15:45 ` [syzbot] WARNING in mntput_no_expire (2) Christian Brauner
2021-04-01 16:09 ` Jens Axboe
2021-04-01 17:46 ` Christian Brauner
2021-04-01 17:59 ` Christian Brauner
2021-04-01 19:11 ` Al Viro
2021-04-04 2:34 ` Al Viro
2021-04-04 2:38 ` Al Viro
2021-04-04 11:34 ` Christian Brauner
2021-04-04 15:56 ` Al Viro
2021-04-04 16:40 ` Christian Brauner
2021-04-04 16:44 ` Al Viro
2021-04-04 17:05 ` Christian Brauner [this message]
2021-04-04 18:50 ` Al Viro
2021-04-04 20:17 ` Al Viro
2021-04-05 11:44 ` Christian Brauner
2021-04-05 16:18 ` Al Viro
2021-04-05 17:08 ` Christian Brauner
2021-04-05 18:23 ` Al Viro
2021-04-05 18:28 ` Al Viro
2021-04-05 20:07 ` Christian Brauner
2021-04-06 1:38 ` Al Viro
2021-04-06 2:24 ` Al Viro
2021-04-06 12:35 ` Christian Brauner
2021-04-06 13:13 ` Al Viro
2021-04-06 13:22 ` Christian Brauner
2021-04-06 14:15 ` Al Viro
2021-04-06 14:23 ` Al Viro
2021-04-06 15:37 ` Jens Axboe
2021-04-06 14:46 ` Christian Brauner
2021-04-04 16:52 ` Christian Brauner
2021-04-04 16:55 ` Christian Brauner
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