netdev - Re: [PATCH] tracepoint: Do not fail unregistering a probe due to memory allocation

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]

Message-ID: <202011171330.94C6BA7E93@keescook>
Date:   Tue, 17 Nov 2020 13:33:42 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Matt Mullins <mmullins@...x.us>,
        Ingo Molnar <mingo@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        netdev <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH] tracepoint: Do not fail unregistering a probe due to
 memory allocation

On Mon, Nov 16, 2020 at 05:51:07PM -0500, Steven Rostedt wrote:
> [ Kees, I added you because you tend to know about these things.
>   Is it OK to assign a void func(void) that doesn't do anything and returns
>   nothing to a function pointer that could be call with parameters? We need
>   to add stubs for tracepoints when we fail to allocate a new array on
>   removal of a callback, but the callbacks do have arguments, but the stub
>   called does not have arguments.
> 
>   Matt, Does this patch fix the error your patch was trying to fix?
> ]

As I think got discussed in the thread, what you had here wouldn't work
in a CFI build if the function prototype of the call site and the
function don't match. (Though I can't tell if .func() is ever called?)

i.e. .func's prototype must match tp_stub_func()'s.

-- 
Kees Cook