From: Takashi Iwai <tiwai@suse.de>
To: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org,
Takashi Iwai <tiwai@suse.com>
Subject: Re: [PATCH][next] ALSA: vmaster: Use flex_array_size() helper in memcpy()
Date: Thu, 30 Jul 2020 10:41:53 +0200 [thread overview]
Message-ID: <s5h1rkte6ni.wl-tiwai@suse.de> (raw)
In-Reply-To: <20200729221829.GA10623@embeddedor>
On Thu, 30 Jul 2020 00:18:29 +0200,
Gustavo A. R. Silva wrote:
>
> Make use of the flex_array_size() helper to calculate the size of a
> flexible array member within an enclosing structure.
>
> This helper offers defense-in-depth against potential integer overflows
> and makes it explicitly clear that we are dealing with a flexible array
> member.
>
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> ---
> sound/core/vmaster.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
> index ab36f9898711..21ce4082cb5f 100644
> --- a/sound/core/vmaster.c
> +++ b/sound/core/vmaster.c
> @@ -262,7 +262,8 @@ int _snd_ctl_add_follower(struct snd_kcontrol *master,
> return -ENOMEM;
> srec->kctl = follower;
> srec->follower = *follower;
> - memcpy(srec->follower.vd, follower->vd, follower->count * sizeof(*follower->vd));
> + memcpy(srec->follower.vd, follower->vd, flex_array_size(srec, follower.vd,
> + srec->follower.count));
Changing from follower->count to srec->follower.count isn't obvious,
so it should have been mentioned in the log; other than that, the code
change looks good.
But since the API isn't in Linus tree yet, I'll postpone the merge
until the API reaches to upstream. Maybe I can merge this during RC1
merge window, as those are trivial.
BTW, looking at those patterns, I wonder whether it'd make sense to
make the whole memset() call as a macro like
safe_copy_array(srec->follower.vd, follower->vd, follower->count);
?
thanks,
Takashi
next prev parent reply other threads:[~2020-07-30 8:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-29 22:18 [PATCH][next] ALSA: vmaster: Use flex_array_size() helper in memcpy() Gustavo A. R. Silva
2020-07-30 8:41 ` Takashi Iwai [this message]
2020-07-30 13:12 ` Gustavo A. R. Silva
2020-07-30 14:57 ` Takashi Iwai
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