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Message-ID: <182680296de.8276ed8742454.8804921618540697946@siddh.me>
Date: Thu, 04 Aug 2022 14:09:36 +0530
From: Siddh Raman Pant <code@...dh.me>
To: "Eric Biggers" <ebiggers@...nel.org>
Cc: "David Howells" <dhowells@...hat.com>,
"Christophe JAILLET" <christophe.jaillet@...adoo.fr>,
"Eric Dumazet" <edumazet@...gle.com>,
"Fabio M. De Francesco" <fmdefrancesco@...il.com>,
"linux-security-modules" <linux-security-module@...r.kernel.org>,
"linux-kernel" <linux-kernel@...r.kernel.org>,
"linux-kernel-mentees"
<linux-kernel-mentees@...ts.linuxfoundation.org>,
"syzbot+c70d87ac1d001f29a058"
<syzbot+c70d87ac1d001f29a058@...kaller.appspotmail.com>
Subject: Re: [PATCH v3] kernel/watch_queue: Make pipe NULL while clearing
watch_queue
On Wed, 03 Aug 2022 23:45:31 +0530 Eric Biggers wrote:
> Well, you should try listening instead. Because you are not listening.
Sorry for that, never meant to come across like that.
> Even if wqueue->pipe was set to NULL during free_pipe_info(), there would still
> have been a use-after-free, as the real bug was the lack of synchronization
> between post_one_notification() and free_pipe_info(). That is fixed now.
Okay, noted.
> To re-iterate, I encourage you to send a cleanup patch if you see an
> opportunity. It looks like the state wqueue->defunct==true could be replaced
> with wqueue->pipe==NULL, which would be simpler, so how about doing that? Just
> don't claim that it is "fixing" something, unless it is, as that makes things
> very confusing and difficult for everyone.
Okay, I will do that. That actually seems like a plausible thing to do, in
v2 convo, David Howells had also remarked similarly about `defunct` to a reply.
https://lore.kernel.org/linux-kernel/3565221.1658933355@warthog.procyon.org.uk/
> A reproducer can just be written as a normal program, in C or another language.
> The syzkaller reproducers are really hard to read as they are auto-generated, so
> don't read too much into them -- they're certainly not examples of good code.
>
> - Eric
Okay, noted.
Thanks for your patience, I probably annoyed you.
Thanks,
Siddh
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