From: Andi Kleen <andi@firstfloor.org>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
Andi Kleen <andi@firstfloor.org>, Jiri Olsa <jolsa@kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] fs/proc/kcore.c: Omit kernel text area for hardened usercopy feature
Date: Wed, 7 Sep 2016 09:38:52 -0700 [thread overview]
Message-ID: <20160907163852.GQ5871@two.firstfloor.org> (raw)
In-Reply-To: <20160907073257.GB8619@krava>
> ---
> diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
> index a939f5ed7f89..de07c273f725 100644
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -515,8 +515,20 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
> } else {
> if (kern_addr_valid(start)) {
> unsigned long n;
> + char *buf;
>
> - n = copy_to_user(buffer, (char *)start, tsz);
> + buf = kzalloc(tsz, GFP_KERNEL);
You have to add some limit and a loop, otherwise a user can eat all kernel memory,
or copies > KMALLOC_MAX wouldn't work. Probably only get a single page.
Also don't need kzalloc, kmalloc is sufficient.
-Andi
next prev parent reply other threads:[~2016-09-07 16:38 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-02 12:25 [PATCH] fs/proc/kcore.c: Omit kernel text area for hardened usercopy feature Jiri Olsa
2016-09-02 15:17 ` Andi Kleen
2016-09-02 16:15 ` Jiri Olsa
2016-09-05 8:47 ` Jiri Olsa
2016-09-05 16:27 ` Andi Kleen
2016-09-06 17:56 ` Kees Cook
2016-09-06 18:34 ` Linus Torvalds
2016-09-06 19:41 ` Andi Kleen
2016-09-06 19:48 ` Linus Torvalds
2016-09-07 17:17 ` Kees Cook
2016-09-07 17:24 ` Linus Torvalds
2016-09-07 7:32 ` Jiri Olsa
2016-09-07 16:38 ` Andi Kleen [this message]
2016-09-07 16:58 ` Linus Torvalds
2016-09-07 19:25 ` Jiri Olsa
2016-09-07 21:24 ` Jiri Olsa
2016-09-07 22:52 ` Linus Torvalds
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