From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Olivier Langlois <olivier@trillion01.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
io-uring <io-uring@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jens Axboe <axboe@kernel.dk>,
"Pavel Begunkov>" <asml.silence@gmail.com>
Subject: Re: [PATCH] coredump: Limit what can interrupt coredumps
Date: Mon, 14 Jun 2021 16:10:33 +0200 [thread overview]
Message-ID: <20210614141032.GA13677@redhat.com> (raw)
In-Reply-To: <87sg1p4h0g.fsf_-_@disp2133>
Eric, et al, sorry for delay, I didn't read emails several days.
On 06/10, Eric W. Biederman wrote:
>
> v2: Don't remove the now unnecessary code in prepare_signal.
No, that code is still needed. Otherwise any fatal signal will be
turned into SIGKILL.
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -519,7 +519,7 @@ static bool dump_interrupted(void)
> * but then we need to teach dump_write() to restart and clear
> * TIF_SIGPENDING.
> */
> - return signal_pending(current);
> + return fatal_signal_pending(current) || freezing(current);
> }
Well yes, this is what the comment says.
But note that there is another reason why dump_interrupted() returns true
if signal_pending(), it assumes thagt __dump_emit()->__kernel_write() may
fail anyway if signal_pending() is true. Say, pipe_write(), or iirc nfs,
perhaps something else...
That is why zap_threads() clears TIF_SIGPENDING. Perhaps it should clear
TIF_NOTIFY_SIGNAL as well and we should change io-uring to not abuse the
dumping threads?
Or perhaps we should change __dump_emit() to clear signal_pending() and
restart __kernel_write() if it fails or returns a short write.
Otherwise the change above doesn't look like a full fix to me.
Oleg.
next prev parent reply other threads:[~2021-06-14 14:10 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <192c9697e379bf084636a8213108be6c3b948d0b.camel@trillion01.com>
[not found] ` <9692dbb420eef43a9775f425cb8f6f33c9ba2db9.camel@trillion01.com>
[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 [this message]
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
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] ` <8218f1a245d054c940e25142fd00a5f17238d078.camel@trillion01.com>
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
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