linux-kernel - Re: [PATCH -next] ftrace: Fix potential warning in trace_printk_seq during ftrace

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Message-ID: <20250821105113.1536d567@gandalf.local.home>
Date: Thu, 21 Aug 2025 10:51:13 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Tengda Wu <wutengda@...weicloud.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Mark Rutland
 <mark.rutland@....com>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Ingo Molnar <mingo@...e.hu>, linux-trace-kernel@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] ftrace: Fix potential warning in trace_printk_seq
 during ftrace_dump

On Thu, 21 Aug 2025 09:53:53 +0800
Tengda Wu <wutengda@...weicloud.com> wrote:

> There remains an edge case that concerns me: if size is 0, setting len to
> size - 1 would cause an underflow. Should we handle this edge case?

When the trace_seq is allocated, the size is set to 8K. If size is ever
zero, then there would be no buffer. So no, we should not worry about that
edge case because if it happened then we have a lot of other things to
worry about.

-- Steve