Re: [PATCH] x86/kprobes: Fix 1 byte conditional jump target

From: Nadav Amit <namit@vmware.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
	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>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] x86/kprobes: Fix 1 byte conditional jump target
Date: Wed, 8 Feb 2023 06:58:45 +0000	[thread overview]
Message-ID: <835C41C0-7E42-4220-8F21-D8419937CBEF@vmware.com> (raw)
In-Reply-To: <b1300308-8f29-fa73-5542-25d06925ca84@intel.com>

> On Feb 8, 2023, at 8:56 AM, Dave Hansen <dave.hansen@intel.com> wrote:
> 
> !! External Email
> 
> On 2/7/23 22:34, Nadav Amit wrote:
>> As you said, I guess the change you and Masami proposed can be done on top of
>> this patch, which is (and was) only intended to fix the bug, and should
>> therefore go into 6.2.
> 
> Nadav,
> 
> To fix this issue, you proposed:
> 
>        p->ainsn.rel32 = *(s8 *)&insn->immediate.value;
> 
> But, this is, um, rather obfuscated and potentially less correct
> compared to:
> 
>        p->ainsn.rel32 = insn->immediate.value;
> 
> I'd appreciate it if you could update your patch to do this simpler
> thing and resend, unless there is a strong reason to do what you
> originally proposed.

I thought it makes sense to make this change for all the other cases
in one pass, but whatever makes you happy.

I will send v2 soon.

Thanks again,
Nadav