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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
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References: <20171016181856.12497-1-richard@nod.at> <20171016181856.12497-3-richard@nod.at> <59E51BA3.8040106@iogearbox.net>
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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