From: Jens Axboe <[email protected]>
To: Tony Battersby <[email protected]>,
Olivier Langlois <[email protected]>,
"Eric W. Biederman" <[email protected]>,
Oleg Nesterov <[email protected]>
Cc: Linus Torvalds <[email protected]>,
Linux Kernel Mailing List <[email protected]>,
linux-fsdevel <[email protected]>,
io-uring <[email protected]>,
Alexander Viro <[email protected]>,
"Pavel Begunkov>" <[email protected]>
Subject: Re: [PATCH] coredump: Limit what can interrupt coredumps
Date: Wed, 18 Aug 2021 08:46:30 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 8/18/21 8:37 AM, Tony Battersby wrote:
> On 8/17/21 6:05 PM, Jens Axboe wrote:
>> On 8/17/21 3:39 PM, Tony Battersby wrote:
>>> On 8/17/21 5:28 PM, Jens Axboe wrote:
>>>> Another approach - don't allow TWA_SIGNAL task_work to get queued if
>>>> PF_SIGNALED has been set on the task. This is similar to how we reject
>>>> task_work_add() on process exit, and the callers must be able to handle
>>>> that already.
>>>>
>>>> Can you test this one on top of your 5.10-stable?
>>>>
>>>>
>>>> diff --git a/fs/coredump.c b/fs/coredump.c
>>>> index 07afb5ddb1c4..ca7c1ee44ada 100644
>>>> --- a/fs/coredump.c
>>>> +++ b/fs/coredump.c
>>>> @@ -602,6 +602,14 @@ void do_coredump(const kernel_siginfo_t *siginfo)
>>>> .mm_flags = mm->flags,
>>>> };
>>>>
>>>> + /*
>>>> + * task_work_add() will refuse to add work after PF_SIGNALED has
>>>> + * been set, ensure that we flush any pending TIF_NOTIFY_SIGNAL work
>>>> + * if any was queued before that.
>>>> + */
>>>> + if (test_thread_flag(TIF_NOTIFY_SIGNAL))
>>>> + tracehook_notify_signal();
>>>> +
>>>> audit_core_dumps(siginfo->si_signo);
>>>>
>>>> binfmt = mm->binfmt;
>>>> diff --git a/kernel/task_work.c b/kernel/task_work.c
>>>> index 1698fbe6f0e1..1ab28904adc4 100644
>>>> --- a/kernel/task_work.c
>>>> +++ b/kernel/task_work.c
>>>> @@ -41,6 +41,12 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
>>>> head = READ_ONCE(task->task_works);
>>>> if (unlikely(head == &work_exited))
>>>> return -ESRCH;
>>>> + /*
>>>> + * TIF_NOTIFY_SIGNAL notifications will interfere with
>>>> + * a core dump in progress, reject them.
>>>> + */
>>>> + if ((task->flags & PF_SIGNALED) && notify == TWA_SIGNAL)
>>>> + return -ESRCH;
>>>> work->next = head;
>>>> } while (cmpxchg(&task->task_works, head, work) != head);
>>>>
>>>>
>>> Doesn't compile. 5.10 doesn't have TIF_NOTIFY_SIGNAL.
>> Oh right... Here's one hacked up for the 5.10 TWA_SIGNAL setup. Totally
>> untested...
>>
>> diff --git a/fs/coredump.c b/fs/coredump.c
>> index c6acfc694f65..9e899ce67589 100644
>> --- a/fs/coredump.c
>> +++ b/fs/coredump.c
>> @@ -603,6 +603,19 @@ void do_coredump(const kernel_siginfo_t *siginfo)
>> .mm_flags = mm->flags,
>> };
>>
>> + /*
>> + * task_work_add() will refuse to add work after PF_SIGNALED has
>> + * been set, ensure that we flush any pending TWA_SIGNAL work
>> + * if any was queued before that.
>> + */
>> + if (signal_pending(current) && (current->jobctl & JOBCTL_TASK_WORK)) {
>> + task_work_run();
>> + spin_lock_irq(¤t->sighand->siglock);
>> + current->jobctl &= ~JOBCTL_TASK_WORK;
>> + recalc_sigpending();
>> + spin_unlock_irq(¤t->sighand->siglock);
>> + }
>> +
>> audit_core_dumps(siginfo->si_signo);
>>
>> binfmt = mm->binfmt;
>> diff --git a/kernel/task_work.c b/kernel/task_work.c
>> index 8d6e1217c451..93b3f262eb4a 100644
>> --- a/kernel/task_work.c
>> +++ b/kernel/task_work.c
>> @@ -39,6 +39,12 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
>> head = READ_ONCE(task->task_works);
>> if (unlikely(head == &work_exited))
>> return -ESRCH;
>> + /*
>> + * TWA_SIGNAL notifications will interfere with
>> + * a core dump in progress, reject them.
>> + */
>> + if ((task->flags & PF_SIGNALED) && notify == TWA_SIGNAL)
>> + return -ESRCH;
>> work->next = head;
>> } while (cmpxchg(&task->task_works, head, work) != head);
>>
>>
> Tested with 5.10.59 + backport 06af8679449d + the patch above. That
> fixes it for me. I tested a couple of variations to make sure.
>
> Thanks!
>
> Tested-by: Tony Battersby <[email protected]>
Great, thanks for testing! The 5.10 version is a bit uglier due to how
TWA_SIGNAL used to work, but it's the most straight forward backport of
the other version I sent.
--
Jens Axboe
next prev parent reply other threads:[~2021-08-18 14:46 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <[email protected]>
[not found] ` <[email protected]>
[not found] ` <87h7i694ij.fsf_-_@disp2133>
2021-06-09 20:33 ` [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL Linus Torvalds
2021-06-09 20:48 ` Eric W. Biederman
2021-06-09 20:52 ` Linus Torvalds
2021-06-09 21:02 ` Olivier Langlois
2021-06-09 21:05 ` Eric W. Biederman
2021-06-09 21:26 ` Olivier Langlois
2021-06-09 21:56 ` Olivier Langlois
2021-06-10 14:26 ` Eric W. Biederman
2021-06-10 15:17 ` Olivier Langlois
2021-06-10 18:58 ` [CFT}[PATCH] coredump: Limit what can interrupt coredumps Eric W. Biederman
2021-06-10 19:10 ` Linus Torvalds
2021-06-10 19:18 ` Eric W. Biederman
2021-06-10 19:50 ` Linus Torvalds
2021-06-10 20:11 ` [PATCH] " Eric W. Biederman
2021-06-10 21:04 ` Linus Torvalds
2021-06-12 14:36 ` Olivier Langlois
2021-06-12 16:26 ` Jens Axboe
2021-06-14 14:10 ` Oleg Nesterov
2021-06-14 16:37 ` Eric W. Biederman
2021-06-14 16:59 ` Oleg Nesterov
2021-06-15 22:08 ` Eric W. Biederman
2021-06-16 19:23 ` Olivier Langlois
2021-06-16 20:00 ` Eric W. Biederman
2021-06-18 20:05 ` Olivier Langlois
2021-08-05 13:06 ` Olivier Langlois
2021-08-10 21:48 ` Tony Battersby
2021-08-11 20:47 ` Olivier Langlois
2021-08-12 1:55 ` Jens Axboe
2021-08-12 13:53 ` Tony Battersby
2021-08-15 20:42 ` Olivier Langlois
2021-08-16 13:02 ` Pavel Begunkov
2021-08-16 13:06 ` Pavel Begunkov
2021-08-17 18:15 ` Jens Axboe
2021-08-17 18:24 ` Jens Axboe
2021-08-17 19:29 ` Tony Battersby
2021-08-17 19:59 ` Jens Axboe
2021-08-17 21:28 ` Jens Axboe
2021-08-17 21:39 ` Tony Battersby
2021-08-17 22:05 ` Jens Axboe
2021-08-18 14:37 ` Tony Battersby
2021-08-18 14:46 ` Jens Axboe [this message]
2021-08-18 2:57 ` Jens Axboe
2021-08-18 2:58 ` Jens Axboe
2021-08-21 10:08 ` Olivier Langlois
2021-08-21 16:47 ` Olivier Langlois
2021-08-21 16:51 ` Jens Axboe
2021-08-21 17:21 ` Olivier Langlois
2021-08-21 9:52 ` Olivier Langlois
2021-08-21 9:48 ` Olivier Langlois
2021-10-22 14:13 ` [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL Pavel Begunkov
2021-12-24 1:34 ` Olivier Langlois
2021-12-24 10:37 ` Pavel Begunkov
2021-12-24 19:52 ` Eric W. Biederman
2021-12-28 11:24 ` Pavel Begunkov
2022-03-14 23:58 ` Eric W. Biederman
[not found] ` <[email protected]>
2022-06-01 3:15 ` Jens Axboe
2022-07-20 16:49 ` [PATCH 0/2] coredump: Allow io_uring using apps to dump to pipes Eric W. Biederman
2022-07-20 16:50 ` [PATCH 1/2] signal: Move stopping for the coredump from do_exit into get_signal Eric W. Biederman
2022-07-20 16:51 ` [PATCH 2/2] coredump: Allow coredumps to pipes to work with io_uring Eric W. Biederman
2022-08-22 21:16 ` Olivier Langlois
2022-08-23 3:35 ` Olivier Langlois
2022-08-23 18:22 ` Eric W. Biederman
2022-08-23 18:27 ` Jens Axboe
2022-08-24 15:11 ` Eric W. Biederman
2022-08-24 15:51 ` Jens Axboe
2022-01-05 19:39 ` [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL Olivier Langlois
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 \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
/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