Building the Linux kernel with Clang and LLVM
 help / color / mirror / Atom feed
From: "Arnd Bergmann" <arnd@arndb.de>
To: "Takashi Iwai" <tiwai@suse.de>, "Arnd Bergmann" <arnd@kernel.org>
Cc: "Jaroslav Kysela" <perex@perex.cz>,
	"Takashi Iwai" <tiwai@suse.com>,
	"Nathan Chancellor" <nathan@kernel.org>,
	"Nick Desaulniers" <nick.desaulniers+lkml@gmail.com>,
	"Bill Wendling" <morbo@google.com>,
	"Justin Stitt" <justinstitt@google.com>,
	linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org,
	llvm@lists.linux.dev
Subject: Re: [PATCH] ALSA: asihpi: avoid write overflow check warning
Date: Wed, 18 Mar 2026 13:16:14 +0100	[thread overview]
Message-ID: <74923a6e-fdce-4f15-b345-55fddcc4c7c2@app.fastmail.com> (raw)
In-Reply-To: <87eclhcpzo.wl-tiwai@suse.de>

On Wed, Mar 18, 2026, at 12:54, Takashi Iwai wrote:
> On Wed, 18 Mar 2026 11:50:08 +0100,

>> +	memcpy(&rESP_HPI_ADAPTER_OPEN[adapter].h, &hr,
>> +		sizeof(rESP_HPI_ADAPTER_OPEN[adapter].h));
>> +	memcpy(&rESP_HPI_ADAPTER_OPEN[adapter].a, &hr.u.s,
>> +		sizeof(rESP_HPI_ADAPTER_OPEN[adapter].a));
>
> I think the last one is still a bit confusing as if doing an overflow
> copy again: hr.u.s is struct hpi_subsys_res which is smaller than
> rESP_HPI_ADAPTER_OPEN[adapter].a which is struct hpi_adapter_res.

Right, I got confused by the various similarly named types
again.

> If any, the last one should be
>
> 	memcpy(&rESP_HPI_ADAPTER_OPEN[adapter].a, &hr.u.ax.info,
> 		sizeof(rESP_HPI_ADAPTER_OPEN[adapter].a));
>
> Or it could be even
>
> 	rESP_HPI_ADAPTER_OPEN[adapter].a = hr.u.ax.info;
>
> (I'm not sure which one can be a better result, though.)

Code generation wise, I would expect them to be the same,
as gcc is good at transforming the memcpy() calls into
direct copies and vice versa.

I'll send a v2 with the first one after it passes build tests,
unless someone has another preference.

      Arnd

      reply	other threads:[~2026-03-18 12:16 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-18 10:50 [PATCH] ALSA: asihpi: avoid write overflow check warning Arnd Bergmann
2026-03-18 11:54 ` Takashi Iwai
2026-03-18 12:16   ` Arnd Bergmann [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=74923a6e-fdce-4f15-b345-55fddcc4c7c2@app.fastmail.com \
    --to=arnd@arndb.de \
    --cc=arnd@kernel.org \
    --cc=justinstitt@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-sound@vger.kernel.org \
    --cc=llvm@lists.linux.dev \
    --cc=morbo@google.com \
    --cc=nathan@kernel.org \
    --cc=nick.desaulniers+lkml@gmail.com \
    --cc=perex@perex.cz \
    --cc=tiwai@suse.com \
    --cc=tiwai@suse.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox