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From: Nadav Amit <nadav.amit@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>
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>
Subject: Re: [PATCH] x86/kprobes: Fix 1 byte conditional jump target
Date: Sun, 5 Feb 2023 09:49:56 +0200	[thread overview]
Message-ID: <5DFB6E19-210E-4EA8-8D71-66FF4A787942@gmail.com> (raw)
In-Reply-To: <20230204210807.3930-1-namit@vmware.com>



> 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.


  reply	other threads:[~2023-02-05  7:50 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-04 21:08 [PATCH] x86/kprobes: Fix 1 byte conditional jump target Nadav Amit
2023-02-05  7:49 ` Nadav Amit [this message]
2023-02-06 14:19   ` Masami Hiramatsu
2023-02-06 14:18 ` Masami Hiramatsu
2023-02-06 18:42 ` Dave Hansen
2023-02-06 19:05   ` Nadav Amit
2023-02-06 22:38     ` Dave Hansen
2023-02-07  0:54       ` Masami Hiramatsu
2023-02-07 15:21         ` Masami Hiramatsu
2023-02-07 15:33           ` Dave Hansen
2023-02-08  6:34             ` Nadav Amit
2023-02-08  6:56               ` Dave Hansen
2023-02-08  6:58                 ` Nadav Amit

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