linux-kernel - Re: violating function pointer signature

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: <20201118150236.65a538eb@gandalf.local.home>
Date:   Wed, 18 Nov 2020 15:02:36 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Florian Weimer <fw@...eb.enyo.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        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>,
        Kees Cook <keescook@...omium.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        linux-toolchains@...r.kernel.org
Subject: Re: violating function pointer signature

On Wed, 18 Nov 2020 11:46:02 -0800
Alexei Starovoitov <alexei.starovoitov@...il.com> wrote:

> On Wed, Nov 18, 2020 at 6:22 AM Steven Rostedt <rostedt@...dmis.org> wrote:
> >
> > Thus, all functions will be non-variadic in these cases.  
> 
> That's not the only case where it will blow up.
> Try this on sparc:
> struct foo {
> int a;
> };
> 
> struct foo foo_struct(void) {
> struct foo f = {};
> return f;
> }
> int foo_int(void) {
> return 0;
> }
> or this link:
> https://godbolt.org/z/EdM47b
> 
> Notice:
> jmp %i7+12
> The function that returns small struct will jump to a different
> instruction in the caller.
> 
> I think none of the tracepoints return structs and void foo(void) is
> fine on x86.
> Just pointing out that it's more than just variadic.

I also said that this is limited to only functions that have void return.

-- Steve