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From: Richard Weinberger <richard@nod.at>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ast@kernel.org
Subject: Re: [PATCH 3/3] bpf: Make sure that ->comm does not change under us.
Date: Mon, 16 Oct 2017 22:55:43 +0200	[thread overview]
Message-ID: <3636052.F7cf4ubS1t@blindfold> (raw)
In-Reply-To: <59E51BA3.8040106@iogearbox.net>

Am Montag, 16. Oktober 2017, 22:50:43 CEST schrieb Daniel Borkmann:
> >   	struct task_struct *task = current;
> > 
> > +	task_lock(task);
> > 
> >   	strncpy(buf, task->comm, size);
> > 
> > +	task_unlock(task);
> 
> Wouldn't this potentially lead to a deadlock? E.g. you attach yourself
> to task_lock() / spin_lock() / etc, and then the BPF prog triggers the
> bpf_get_current_comm() taking the lock again ...

Yes, but doesn't the same apply to the use case when I attach to strncpy()
and run bpf_get_current_comm()?

Thanks,
//richard

  reply	other threads:[~2017-10-16 20:55 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-16 18:18 [PATCH 1/3] bpf: Don't check for current being NULL Richard Weinberger
2017-10-16 18:18 ` [PATCH 2/3] bpf: Remove dead variable Richard Weinberger
2017-10-16 18:54   ` Daniel Borkmann
2017-10-16 18:59     ` Richard Weinberger
2017-10-16 19:11       ` Daniel Borkmann
2017-10-16 19:22         ` Richard Weinberger
2017-10-16 20:48           ` Daniel Borkmann
2017-10-16 18:18 ` [PATCH 3/3] bpf: Make sure that ->comm does not change under us Richard Weinberger
2017-10-16 20:50   ` Daniel Borkmann
2017-10-16 20:55     ` Richard Weinberger [this message]
2017-10-16 21:02       ` Daniel Borkmann
2017-10-16 21:10         ` Richard Weinberger
  -- strict thread matches above, loose matches on Subject: below --
2017-10-16 22:10 Alexei Starovoitov
2017-10-16 22:19 ` Daniel Borkmann

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