linux-kernel - Re: [PATCH 2/2] tracing: Stop fortify-string from warning in tracing_mark_raw

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Message-ID: <20251013130536.591e4253@gandalf.local.home>
Date: Mon, 13 Oct 2025 13:05:36 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Steven Rostedt <rostedt@...nel.org>, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Andrew Morton
 <akpm@...ux-foundation.org>, stable@...r.kernel.org,
 syzbot+9a2ede1643175f350105@...kaller.appspotmail.com
Subject: Re: [PATCH 2/2] tracing: Stop fortify-string from warning in
 tracing_mark_raw_write()

On Sun, 12 Oct 2025 12:34:08 +0900
Masami Hiramatsu (Google) <mhiramat@...nel.org> wrote:

> > Use a void pointer and get the offset via offsetof() to keep fortify
> > string from warning about this copy.
> > 
> > Cc: stable@...r.kernel.org
> > Fixes: 64cf7d058a00 ("tracing: Have trace_marker use per-cpu data to read user space")
> > Reported-by: syzbot+9a2ede1643175f350105@...kaller.appspotmail.com
> > Closes: https://lore.kernel.org/all/68e973f5.050a0220.1186a4.0010.GAE@google.com/
> > Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>  
> 
> Ah, fixed already.
> 
> Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Actually this was the wrong fix. Before submitting a pull request, I looked
to see if there was a better way to handle this and discovered "unsafe_memcpy()"
which is the proper solution:

  https://lore.kernel.org/all/20251011112032.77be18e4@gandalf.local.home/

-- Steve