From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: alsa-devel@alsa-project.org, Dan Carpenter <error27@gmail.com>,
Jassi Brar <jassi.brar@samsung.com>,
kernel-janitors@vger.kernel.org,
Peter Ujfalusi <peter.ujfalusi@nokia.com>,
linux-kernel@vger.kernel.org, Liam Girdwood <lrg@slimlogic.co.uk>
Subject: Re: [patch] ASoC: soc: snprintf() doesn't return negative
Date: Tue, 12 Oct 2010 10:56:05 +0100 [thread overview]
Message-ID: <20101012095605.GC30933@rakim.wolfsonmicro.main> (raw)
In-Reply-To: <s5hvd57eo60.wl%tiwai@suse.de>
On Tue, Oct 12, 2010 at 11:49:27AM +0200, Takashi Iwai wrote:
> Mark Brown wrote:
> Argh, yes, I'm (again) confused by that behavior.
> The problem is the potential buffer overflow, indeed. snprintf()
> returns the size that would be printed. Thus a safe code would be
> like:
>
> list_for_each_entry(dai, &dai_list, list) {
> int len = snprintf(buf + ret, PAGE_SIZE - ret, "%s\n", dai->name);
> if (len < 0)
> continue;
> ret += len;
> if (ret >= PAGE_SIZE) {
> ret = PAGE_SIZE;
> break;
> }
> }
Yes, this form is better for that variant of the loop - that is safe and
legible without relying on current implementation details of snprintf().
WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: alsa-devel@alsa-project.org, Dan Carpenter <error27@gmail.com>,
Jassi Brar <jassi.brar@samsung.com>,
kernel-janitors@vger.kernel.org,
Peter Ujfalusi <peter.ujfalusi@nokia.com>,
linux-kernel@vger.kernel.org, Liam Girdwood <lrg@slimlogic.co.uk>
Subject: Re: [patch] ASoC: soc: snprintf() doesn't return negative
Date: Tue, 12 Oct 2010 09:56:05 +0000 [thread overview]
Message-ID: <20101012095605.GC30933@rakim.wolfsonmicro.main> (raw)
In-Reply-To: <s5hvd57eo60.wl%tiwai@suse.de>
On Tue, Oct 12, 2010 at 11:49:27AM +0200, Takashi Iwai wrote:
> Mark Brown wrote:
> Argh, yes, I'm (again) confused by that behavior.
> The problem is the potential buffer overflow, indeed. snprintf()
> returns the size that would be printed. Thus a safe code would be
> like:
>
> list_for_each_entry(dai, &dai_list, list) {
> int len = snprintf(buf + ret, PAGE_SIZE - ret, "%s\n", dai->name);
> if (len < 0)
> continue;
> ret += len;
> if (ret >= PAGE_SIZE) {
> ret = PAGE_SIZE;
> break;
> }
> }
Yes, this form is better for that variant of the loop - that is safe and
legible without relying on current implementation details of snprintf().
WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: Dan Carpenter <error27@gmail.com>,
Liam Girdwood <lrg@slimlogic.co.uk>,
Jaroslav Kysela <perex@perex.cz>,
Peter Ujfalusi <peter.ujfalusi@nokia.com>,
Jassi Brar <jassi.brar@samsung.com>,
alsa-devel@alsa-project.org, kernel-janitors@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch] ASoC: soc: snprintf() doesn't return negative
Date: Tue, 12 Oct 2010 10:56:05 +0100 [thread overview]
Message-ID: <20101012095605.GC30933@rakim.wolfsonmicro.main> (raw)
In-Reply-To: <s5hvd57eo60.wl%tiwai@suse.de>
On Tue, Oct 12, 2010 at 11:49:27AM +0200, Takashi Iwai wrote:
> Mark Brown wrote:
> Argh, yes, I'm (again) confused by that behavior.
> The problem is the potential buffer overflow, indeed. snprintf()
> returns the size that would be printed. Thus a safe code would be
> like:
>
> list_for_each_entry(dai, &dai_list, list) {
> int len = snprintf(buf + ret, PAGE_SIZE - ret, "%s\n", dai->name);
> if (len < 0)
> continue;
> ret += len;
> if (ret >= PAGE_SIZE) {
> ret = PAGE_SIZE;
> break;
> }
> }
Yes, this form is better for that variant of the loop - that is safe and
legible without relying on current implementation details of snprintf().
next prev parent reply other threads:[~2010-10-12 9:56 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-11 3:54 [patch] ASoC: soc: snprintf() doesn't return negative Dan Carpenter
2010-10-11 3:54 ` Dan Carpenter
2010-10-11 10:07 ` Liam Girdwood
2010-10-11 10:07 ` Liam Girdwood
2010-10-11 10:40 ` Mark Brown
2010-10-11 10:40 ` Mark Brown
2010-10-11 16:40 ` Dan Carpenter
2010-10-11 16:40 ` Dan Carpenter
2010-10-11 16:40 ` Dan Carpenter
2010-10-11 18:51 ` Mark Brown
2010-10-11 18:51 ` Mark Brown
2010-10-11 18:51 ` Mark Brown
2010-10-11 19:45 ` Dan Carpenter
2010-10-11 19:45 ` Dan Carpenter
2010-10-11 19:45 ` Dan Carpenter
2010-10-11 20:57 ` Takashi Iwai
2010-10-11 20:57 ` Takashi Iwai
2010-10-11 20:57 ` Takashi Iwai
2010-10-12 9:35 ` Mark Brown
2010-10-12 9:35 ` Mark Brown
2010-10-12 9:35 ` Mark Brown
2010-10-12 9:49 ` Takashi Iwai
2010-10-12 9:49 ` Takashi Iwai
2010-10-12 9:49 ` Takashi Iwai
2010-10-12 9:56 ` Mark Brown [this message]
2010-10-12 9:56 ` Mark Brown
2010-10-12 9:56 ` Mark Brown
2010-10-12 10:40 ` Dan Carpenter
2010-10-12 10:40 ` Dan Carpenter
2010-10-12 10:40 ` Dan Carpenter
2010-10-11 21:11 ` Dan Carpenter
2010-10-11 21:11 ` Dan Carpenter
2010-10-11 21:11 ` Dan Carpenter
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