From: Al Viro <viro@zeniv.linux.org.uk>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Jens Axboe <axboe@kernel.dk>,
syzbot <syzbot+c88a7030da47945a3cc3@syzkaller.appspotmail.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, io-uring@vger.kernel.org
Subject: Re: [syzbot] WARNING in mntput_no_expire (2)
Date: Sun, 4 Apr 2021 02:38:30 +0000 [thread overview]
Message-ID: <YGkmpv1xNrTExS6l@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <YGkloJhMFc4hEatk@zeniv-ca.linux.org.uk>
On Sun, Apr 04, 2021 at 02:34:08AM +0000, Al Viro wrote:
> I really wonder what mount is it happening to. BTW, how painful would
> it be to teach syzcaller to turn those cascades of
> NONFAILING(*(uint8_t*)0x20000080 = 0x12);
> NONFAILING(*(uint8_t*)0x20000081 = 0);
> NONFAILING(*(uint16_t*)0x20000082 = 0);
> NONFAILING(*(uint32_t*)0x20000084 = 0xffffff9c);
> NONFAILING(*(uint64_t*)0x20000088 = 0);
> NONFAILING(*(uint64_t*)0x20000090 = 0x20000180);
> NONFAILING(memcpy((void*)0x20000180, "./file0\000", 8));
> NONFAILING(*(uint32_t*)0x20000098 = 0);
> NONFAILING(*(uint32_t*)0x2000009c = 0x80);
> NONFAILING(*(uint64_t*)0x200000a0 = 0x23456);
> ....
> NONFAILING(syz_io_uring_submit(r[1], r[2], 0x20000080, 0));
> into something more readable? Bloody annoyance every time... Sure, I can
> manually translate it into
> struct io_uring_sqe *sqe = (void *)0x20000080;
> char *s = (void *)0x20000180;
> memset(sqe, '\0', sizeof(*sqe));
> sqe->opcode = 0x12; // IORING_OP_OPENAT?
> sqe->fd = -100; // AT_FDCWD?
> sqe->addr = s;
> strcpy(s, "./file0");
> sqe->open_flags = 0x80; // O_EXCL???
> sqe->user_data = 0x23456; // random tag?
> syz_io_uring_submit(r[1], r[2], (unsigned long)p, 0);
> but it's really annoying as hell, especially since syz_io_uring_submit()
> comes from syzcaller and the damn thing _knows_ that the third argument
> is sodding io_uring_sqe, and never passed to anything other than
> memcpy() in there, at that, so the exact address can't matter.
... especially since the native syzcaller reproducer clearly *does* have
that information. Simply putting that into comments side-by-side with
what gets put into C reproducer would be nice, especially if it goes with
field names...
next prev parent reply other threads:[~2021-04-04 2:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 9:09 [syzbot] WARNING in mntput_no_expire (2) syzbot
2021-04-01 12:16 ` syzbot
2021-04-01 18:32 ` Christian Brauner
2021-04-01 15:45 ` 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 [this message]
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
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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