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From: Joe Perches <joe@perches.com>
To: Julia Lawall <julia.lawall@inria.fr>, Denis Efremov <efremov@linux.com>
Cc: Kees Cook <keescook@chromium.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	linux-kernel@vger.kernel.org, Alex Dewar <alex.dewar90@gmail.com>,
	accessrunner-general@lists.sourceforge.net,
	cocci <cocci@systeme.lip6.fr>
Subject: Re: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs
Date: Thu, 27 Aug 2020 14:44:01 -0700	[thread overview]
Message-ID: <d6d5836196208d5280cedf5837952096c3518852.camel@perches.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2008272334500.2482@hadrien>

On Thu, 2020-08-27 at 23:36 +0200, Julia Lawall wrote:
> On Fri, 28 Aug 2020, Denis Efremov wrote:
[]
> Regarding current device_attr_show.cocci implementation, it detects the functions
> > by declaration:
> > ssize_t any_name(struct device *dev, struct device_attribute *attr, char *buf)
> > 
> > and I limited the check to:
> > "return snprintf"
> > pattern because there are already too many warnings.
> > 
> > Actually, it looks more correct to check for:
> > ssize_t show(struct device *dev, struct device_attribute *attr, char *buf)
> > {
> >         <...
> > *       snprintf@p(...);
> >         ...>
> > }
> > 
> > This pattern should also highlight the snprintf calls there we save returned
> > value in a var, e.g.:
> > 
> > ret += snprintf(...);
> > ...
> > ret += snprintf(...);
> > ...
> > ret += snprintf(...);
> > 
> > return ret;
> > 
> > > Something like
> > > 
> > > identifier f;
> > > fresh identifier = "sysfs" ## f;
> > > 
> > > may be useful.  Let me know if further help is needed.
> > 
> > Initially, I wrote the rule to search for DEVICE_ATTR(..., ..., func_name, ...)
> 
> This is what I would have expected.
> 
> > functions. However, it looks like matching function prototype is enough. At least,
> > I failed to find false positives. I rejected the initial DEVICE_ATTR() searching
> > because I thought that it's impossible to handle DEVICE_ATTR_RO()/DEVICE_ATTR_RW()
> > macroses with coccinelle as they "generate" function names internally with
> > "##". "fresh identifier" should really help here, but now I doubt it's required in
> > device_attr_show.cocci, function prototype is enough.
> 
> It's true that it is probably unique enough.

I tried:
@@
identifier f_show =~ "^.*_show$";
identifier dev, attr, buf;
const char *chr;
@@
ssize_t f_show(struct device *dev, struct device_attribute *attr, char
*buf)
{
	<...
(
-	sprintf
+	sysfs_sprintf
	(...);
|
-	snprintf(buf, PAGE_SIZE,
+	sysfs_sprintf(buf,
	...);
|
-	scnprintf(buf, PAGE_SIZE,
+	sysfs_sprintf(buf,
	...);
|
	strcpy(buf, chr);
	sysfs_strcpy(buf, chr);
)
	...>
}

which finds direct statements without an assign
but that doesn't find

arch/arm/common/dmabounce.c:static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr, char *buf)
arch/arm/common/dmabounce.c-{
arch/arm/common/dmabounce.c-    struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
arch/arm/common/dmabounce.c-    return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
arch/arm/common/dmabounce.c-            device_info->small.allocs,
arch/arm/common/dmabounce.c-            device_info->large.allocs,
arch/arm/common/dmabounce.c-            device_info->total_allocs - device_info->small.allocs -
arch/arm/common/dmabounce.c-                    device_info->large.allocs,
arch/arm/common/dmabounce.c-            device_info->total_allocs,
arch/arm/common/dmabounce.c-            device_info->map_op_count,
arch/arm/common/dmabounce.c-            device_info->bounce_count);
arch/arm/common/dmabounce.c-}


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  reply	other threads:[~2020-08-27 21:44 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200824222322.22962-1-alex.dewar90@gmail.com>
     [not found] ` <48f2dc90-7852-eaf1-55d7-2c85cf954688@rasmusvillemoes.dk>
     [not found]   ` <20200827071537.GA168593@kroah.com>
     [not found]     ` <20200827131819.7rcl2f5js3hkoqj2@lenovo-laptop>
     [not found]       ` <def24e9e-018c-9712-0d07-d4cbc84f07d9@rasmusvillemoes.dk>
     [not found]         ` <20200827144846.yauuttjaqtxaldxg@lenovo-laptop>
2020-08-27 16:58           ` [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs Joe Perches
2020-08-27 19:42             ` Julia Lawall
2020-08-27 20:29               ` Joe Perches
2020-08-27 21:00                 ` Joe Perches
2020-08-27 21:29                 ` Julia Lawall
2020-08-27 22:03                 ` David Laight
2020-08-27 22:11                   ` Joe Perches
2020-08-27 22:16                     ` Kees Cook
2020-08-27 21:01               ` Denis Efremov
2020-08-27 21:36                 ` Julia Lawall
2020-08-27 21:44                   ` Joe Perches [this message]
2020-08-27 22:38                     ` Denis Efremov
2020-08-27 22:48                       ` Joe Perches
2020-08-27 22:20                 ` Kees Cook
2020-08-27 22:45                   ` Joe Perches
2020-08-28  4:12                     ` Joe Perches
2020-08-28  7:58                       ` Kees Cook
2020-08-28  8:10                         ` Joe Perches
2020-08-28  8:22                           ` Joe Perches
2020-08-28  7:39                   ` David Laight
2020-08-27 21:54             ` David Laight

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