Content-Type: text/plain;
        charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3731.300.101.1.3\))
Subject: Re: [PATCH] x86/kprobes: Fix 1 byte conditional jump target
From:   Nadav Amit <nadav.amit@gmail.com>
In-Reply-To: <20230204210807.3930-1-namit@vmware.com>
Date:   Sun, 5 Feb 2023 09:49:56 +0200
Cc:     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>
Content-Transfer-Encoding: quoted-printable
Message-Id: <5DFB6E19-210E-4EA8-8D71-66FF4A787942@gmail.com>
References: <20230204210807.3930-1-namit@vmware.com>
To:     Thomas Gleixner <tglx@linutronix.de>
Precedence: bulk


> On Feb 4, 2023, at 11:08 PM, Nadav Amit <nadav.amit@gmail.com> wrote:
>=20
> From: Nadav Amit <namit@vmware.com>
>=20
> 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.
>=20
> Fix by using s8 instead of char and use immediate.value instead of
> immediate.bytes for consistency.

I guess I forgot to put a =E2=80=9CFixes=E2=80=9D 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=E2=80=A6 Please let =
me know
whether v2 is needed with a =E2=80=9Cfixes=E2=80=9D tag.