From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <research_trasio@irq.a4lg.com>
Received: from mail-sender-0.a4lg.com (mail-sender-0.a4lg.com
 [IPv6:2401:2500:203:30b:4000:6bfe:4757:0])
 by sourceware.org (Postfix) with ESMTPS id 7EE793858299
 for <gdb-patches@sourceware.org>; Tue,  4 Oct 2022 09:28:48 +0000 (GMT)
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 7EE793858299
Received: from [127.0.0.1] (localhost [127.0.0.1])
 by mail-sender-0.a4lg.com (Postfix) with ESMTPSA id E0921300089;
 Tue,  4 Oct 2022 09:28:46 +0000 (UTC)
Message-ID: <f91d7a42-84e5-4154-f5e2-8f9289a2fe9d@irq.a4lg.com>
Date: Tue, 4 Oct 2022 18:28:45 +0900
Mime-Version: 1.0
Subject: Re: [PATCH 2/2] gdb/riscv: Fix buffer overflow on
 riscv_insn::fetch_instruction
Content-Language: en-US
To: Andreas Schwab <schwab@suse.de>, gdb-patches@sourceware.org
References: <cover.1664873933.git.research_trasio@irq.a4lg.com>
 <89612fe01d902007bf84a7dfb0df5f85d5c166e4.1664873933.git.research_trasio@irq.a4lg.com>
 <mvm1qrohscy.fsf@suse.de> <29872020-9f00-b639-717e-a31a3e614210@irq.a4lg.com>
 <mvmwn9ggcte.fsf@suse.de>
From: Tsukasa OI <research_trasio@irq.a4lg.com>
In-Reply-To: <mvmwn9ggcte.fsf@suse.de>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
X-Spam-Status: No, score=-6.2 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, SPF_HELO_NONE, SPF_PASS,
 TXREP autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
 server2.sourceware.org
X-BeenThere: gdb-patches@sourceware.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gdb-patches mailing list <gdb-patches.sourceware.org>
List-Unsubscribe: <https://sourceware.org/mailman/options/gdb-patches>,
 <mailto:gdb-patches-request@sourceware.org?subject=unsubscribe>
List-Archive: <https://sourceware.org/pipermail/gdb-patches/>
List-Post: <mailto:gdb-patches@sourceware.org>
List-Help: <mailto:gdb-patches-request@sourceware.org?subject=help>
List-Subscribe: <https://sourceware.org/mailman/listinfo/gdb-patches>,
 <mailto:gdb-patches-request@sourceware.org?subject=subscribe>
X-List-Received-Date: Tue, 04 Oct 2022 09:28:50 -0000

On 2022/10/04 18:25, Andreas Schwab wrote:
> On Okt 04 2022, Tsukasa OI wrote:
> 
>> That's technically possible but it will make something like...
>>     8 + 2 + 2 * ((1 << 3) - 1 - 1)
> 
> That's still a magic number that doesn't adapt.

Exactly.  I could not find any constants to depend to.  If we define
"currently" magic number (22) as RISCV_MAX_INSN_LEN, at least we can
share that constant between Binutils and GDB.

> 
>> Defining RISCV_MAX_INSN_LEN might be a slightly better solution (still,
>> content of RISCV_MAX_INSN_LEN will be a magic number).
> 
> If that number is then used as the base for the other dependencies, it's
> a win.
>