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Date: Tue, 29 Apr 2025 18:31:09 +0200
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Nam Cao <namcao@linutronix.de>
Cc: stable@vger.kernel.org, Kai Zhang <zhangkai@iscas.ac.cn>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>, Alexandre Ghiti <alex@ghiti.fr>,
	Samuel Holland <samuel.holland@sifive.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH stable v6.6] riscv: kprobes: Fix wrong lengths passed to
 patch_text_nosync()
Message-ID: <2025042945-financial-rumbling-bcd0@gregkh>
References: <20250429161418.838564-1-namcao@linutronix.de>
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In-Reply-To: <20250429161418.838564-1-namcao@linutronix.de>

On Tue, Apr 29, 2025 at 06:14:18PM +0200, Nam Cao wrote:
> Unlike patch_text(), patch_text_nosync() takes the length in bytes, not
> number of instructions. It is therefore wrong for arch_prepare_ss_slot() to
> pass length=1 while patching one instruction.
> 
> This bug was introduced by commit b1756750a397 ("riscv: kprobes: Use
> patch_text_nosync() for insn slots"). It has been fixed upstream by commit
> 51781ce8f448 ("riscv: Pass patch_text() the length in bytes"). However,
> beside fixing this bug, this commit does many other things, making it
> unsuitable for backporting.

We would almost always want the original commit, why not just send that
instead?  What is wrong with it being in here as-is?

thanks,

greg k-h