linux-kernel - Re: [RFC PATCH 3/6] bpf: Save the pointer to struct perf

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 17 Jul 2015 13:06:23 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	kaixu xia <xiakaixu@...wei.com>
Cc:	ast@...mgrid.com, davem@...emloft.net, acme@...nel.org,
	mingo@...hat.com, masami.hiramatsu.pt@...achi.com,
	jolsa@...nel.org, wangnan0@...wei.com,
	linux-kernel@...r.kernel.org, pi3orama@....com, hekuang@...wei.com
Subject: Re: [RFC PATCH 3/6] bpf: Save the pointer to struct perf_event to map

On Fri, Jul 17, 2015 at 06:43:33PM +0800, kaixu xia wrote:
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index e965cfa..c4e34b7 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -8582,6 +8582,28 @@ void perf_event_delayed_put(struct task_struct *task)
>  		WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
>  }
>  
> +struct perf_event *perf_event_get(unsigned int fd)
> +{
> +	struct perf_event *event;
> +	struct fd f;
> +
> +	f = fdget(fd);
> +
> +	if (!f.file)
> +		return ERR_PTR(-EBADF);
> +
> +	if (f.file->f_op != &perf_fops) {
> +		fdput(f);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	event = f.file->private_data;
> +
> +	fdput(f);
> +
> +	return event;
> +}

And what is stopping userspace from closing those FDs while you're using
them?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/