From: Christoph Hellwig <hch@lst.de>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Elly I. Esparza" <ellyesparza8@gmail.com>,
linux-kernel@vger.kernel.org, will@kernel.org,
akpm@linux-foundation.org, ast@kernel.org, yangfeng@kylinos.cn,
gregkh@linuxfoundation.org, hch@lst.de, qperret@google.com
Subject: Re: [PATCH 2/2] kernel/kallsyms: Prevent bypassing of kprobes blacklist
Date: Thu, 19 Feb 2026 08:20:09 +0100 [thread overview]
Message-ID: <20260219072009.GA5597@lst.de> (raw)
In-Reply-To: <20260219102915.2a79f0713032d95814eee79f@kernel.org>
On Thu, Feb 19, 2026 at 10:29:15AM +0900, Masami Hiramatsu wrote:
> On Wed, 18 Feb 2026 11:48:19 -0300
> "Elly I. Esparza" <ellyesparza8@gmail.com> wrote:
>
> > Kprobes can be used to get the adress of kallsyms_lookup_name() providing
> > access to blacklisted symbols.
> >
> > Add kallsyms_lookup_name() to kprobes blacklist.
>
> NACK, this NOKPROBE_SYMBOL() should be used for the functions which
> is called inside the kprobe callback handler. kallsyms_lookup_name()
> is used when setting up the kprobe, not from the callbacks.
I don't think that's the point Elly made. The point is that
kallsyms_lookup_name + kprobes is used to bypass lacking symbol exports.
So preventing it is a good idea, and this seems like a cute hack for
that. But it really needs a better commit log, and a big fat comment
explaining the slight abuse of NOKPROBE_SYMBOL in the code.
prev parent reply other threads:[~2026-02-19 7:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-18 14:48 [PATCH 2/2] kernel/kallsyms: Prevent bypassing of kprobes blacklist Elly I. Esparza
2026-02-19 1:29 ` Masami Hiramatsu
2026-02-19 7:20 ` Christoph Hellwig [this message]
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