linux-kernel - Re: [PATCH v2 2/4] fprobe: make fprobe_kprobe

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: <20230517010311.f46db3f78b11cf9d92193527@kernel.org>
Date:   Wed, 17 May 2023 01:03:11 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Ze Gao <zegao2021@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-s390@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        bpf@...r.kernel.org, Conor Dooley <conor@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Yonghong Song <yhs@...com>,
        Ze Gao <zegao@...cent.com>
Subject: Re: [PATCH v2 2/4] fprobe: make fprobe_kprobe_handler recursion
 free

On Tue, 16 May 2023 17:47:52 +0800
Ze Gao <zegao2021@...il.com> wrote:

> Precisely, these that are called within kprobe_busy_{begin, end},
> which the previous patch does not resolve.

Note that kprobe_busy_{begin,end} don't need to use notrace version
because kprobe itself prohibits probing on preempt_count_{add,sub}.

Thank you,

> I will refine the commit message to make it clear.
> 
> FYI, details can checked out here:
>     Link: https://lore.kernel.org/linux-trace-kernel/20230516132516.c902edcf21028874a74fb868@kernel.org/
> 
> Regards,
> Ze
> 
> On Tue, May 16, 2023 at 5:18 PM Peter Zijlstra <peterz@...radead.org> wrote:
> >
> > On Tue, May 16, 2023 at 03:18:28PM +0800, Ze Gao wrote:
> > > Current implementation calls kprobe related functions before doing
> > > ftrace recursion check in fprobe_kprobe_handler, which opens door
> > > to kernel crash due to stack recursion if preempt_count_{add, sub}
> > > is traceable.
> >
> > Which preempt_count*() are you referring to? The ones you just made
> > _notrace in the previous patch?


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>