From: Thomas Gleixner <tglx@linutronix.de>
To: Aleksandr Nogikh <nogikh@google.com>
Cc: syzbot <syzbot+b408cd9b40ec25380ee1@syzkaller.appspotmail.com>,
adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, tytso@mit.edu
Subject: Re: [syzbot] [ext4?] general protection fault in hrtimer_nanosleep
Date: Thu, 02 Nov 2023 16:57:03 +0100 [thread overview]
Message-ID: <87r0l8kv1s.ffs@tglx> (raw)
In-Reply-To: <CANp29Y7EQ0cLf23coqFLLRHbA5rJjq0q1-6G7nnhxqBOUA7apw@mail.gmail.com>
On Thu, Nov 02 2023 at 13:08, Aleksandr Nogikh wrote:
> On Wed, Nov 1, 2023 at 1:58 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>> Unfortunately repro.syz does not hold up to its name and refuses to
>> reproduce.
>
> For me, on a locally built kernel (gcc 13.2.0) it didn't work either.
>
> But, interestingly, it does reproduce using the syzbot-built kernel
> shared via the "Downloadable assets" [1] in the original report. The
> repro crashed the kernel in ~1 minute.
>
> [1] https://github.com/google/syzkaller/blob/master/docs/syzbot_assets.md
>
> [ 125.919060][ C0] BUG: KASAN: stack-out-of-bounds in rb_next+0x10a/0x130
> [ 125.921169][ C0] Read of size 8 at addr ffffc900048e7c60 by task
> kworker/0:1/9
> [ 125.923235][ C0]
> [ 125.923243][ C0] CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted
> 6.6.0-rc7-syzkaller-00142-g888cf78c29e2 #0
> [ 125.924546][ C0] Hardware name: QEMU Standard PC (Q35 + ICH9,
> 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [ 125.926915][ C0] Workqueue: events nsim_dev_trap_report_work
> [ 125.929333][ C0]
> [ 125.929341][ C0] Call Trace:
> [ 125.929350][ C0] <IRQ>
> [ 125.929356][ C0] dump_stack_lvl+0xd9/0x1b0
> [ 125.931302][ C0] print_report+0xc4/0x620
> [ 125.932115][ C0] ? __virt_addr_valid+0x5e/0x2d0
> [ 125.933194][ C0] kasan_report+0xda/0x110
> [ 125.934814][ C0] ? rb_next+0x10a/0x130
> [ 125.936521][ C0] ? rb_next+0x10a/0x130
> [ 125.936544][ C0] rb_next+0x10a/0x130
> [ 125.936565][ C0] timerqueue_del+0xd4/0x140
> [ 125.936590][ C0] __remove_hrtimer+0x99/0x290
> [ 125.936613][ C0] __hrtimer_run_queues+0x55b/0xc10
> [ 125.936638][ C0] ? enqueue_hrtimer+0x310/0x310
> [ 125.936659][ C0] ? ktime_get_update_offsets_now+0x3bc/0x610
> [ 125.936688][ C0] hrtimer_interrupt+0x31b/0x800
> [ 125.936715][ C0] __sysvec_apic_timer_interrupt+0x105/0x3f0
> [ 125.936737][ C0] sysvec_apic_timer_interrupt+0x8e/0xc0
> [ 125.936755][ C0] </IRQ>
> [ 125.936759][ C0] <TASK>
Which is a completely different failure mode.
It explodes in the hrtimer interrupt when dequeuing an hrtimer for
expiry. That means the corresponding embedded rb_node is corrupted,
which points to random data corruption.
As you can reproduce (it still fails here with the provided assets),
does the failure change when you run it several times?
Thanks,
tglx
next prev parent reply other threads:[~2023-11-02 15:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-01 5:36 [syzbot] [ext4?] general protection fault in hrtimer_nanosleep syzbot
2023-11-01 12:58 ` Thomas Gleixner
2023-11-02 12:08 ` Aleksandr Nogikh
2023-11-02 15:57 ` Thomas Gleixner [this message]
2023-11-10 5:00 ` Aleksandr Nogikh
2023-11-10 17:08 ` Theodore Ts'o
2023-11-03 11:17 ` AW: " carsten.schmid
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87r0l8kv1s.ffs@tglx \
--to=tglx@linutronix.de \
--cc=adilger.kernel@dilger.ca \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nogikh@google.com \
--cc=syzbot+b408cd9b40ec25380ee1@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox