linux-kernel - Re: [PATCH] printk: Fix signed integer overflow when defining LOG_BUF_LEN

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Message-ID: <Zvvch303oFPCZnJ-@pathway.suse.cz>
Date: Tue, 1 Oct 2024 13:27:03 +0200
From: Petr Mladek <pmladek@...e.com>
To: Kuan-Wei Chiu <visitorckw@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Ching-Chun Huang <jserv@...s.ncku.edu.tw>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] printk: Fix signed integer overflow when defining
 LOG_BUF_LEN_MAX

On Sat 2024-09-28 19:36:08, Kuan-Wei Chiu wrote:
> Shifting 1 << 31 on a 32-bit int causes signed integer overflow, which
> leads to undefined behavior. To prevent this, cast 1 to u32 before
> performing the shift, ensuring well-defined behavior.
> 
> This change explicitly avoids any potential overflow by ensuring that
> the shift occurs on an unsigned 32-bit integer.
> 
> Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>

Looks good to me.

Acked-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr