Date:   Mon, 6 Feb 2023 23:19:34 +0900
From:   Masami Hiramatsu (Google) <mhiramat@kernel.org>
To:     Nadav Amit <nadav.amit@gmail.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        X86 ML <x86@kernel.org>,
        kernel list <linux-kernel@vger.kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] x86/kprobes: Fix 1 byte conditional jump target
Message-Id: <20230206231934.7ccbf7bf1f31b404783b10f9@kernel.org>
In-Reply-To: <5DFB6E19-210E-4EA8-8D71-66FF4A787942@gmail.com>
References: <20230204210807.3930-1-namit@vmware.com>
        <5DFB6E19-210E-4EA8-8D71-66FF4A787942@gmail.com>
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On Sun, 5 Feb 2023 09:49:56 +0200
Nadav Amit <nadav.amit@gmail.com> wrote:

> 
> 
> > On Feb 4, 2023, at 11:08 PM, Nadav Amit <nadav.amit@gmail.com> wrote:
> > 
> > From: Nadav Amit <namit@vmware.com>
> > 
> > Commit 3bc753c06dd0 ("kbuild: treat char as always unsigned") broke
> > kprobes.  Setting a probe-point on 1 byte conditional jump can cause the
> > kernel to crash, as the branch target is not sign extended.
> > 
> > Fix by using s8 instead of char and use immediate.value instead of
> > immediate.bytes for consistency.
> 
> I guess I forgot to put a “Fixes” tag, since it is still not a real
> regression. (The bug was introduced in 6.2).
> 
> Still, this fix should not fall between the cracks… Please let me know
> whether v2 is needed with a “fixes” tag.

No problem, I added Fixed tag with my Ack :)

Thank you!

> 


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