Re: [PATCH] virtio-blk: fixup coccinelle warnings

[Stefano Garzarella]

On Thu, Oct 21, 2021 at 06:51:11AM +, cgel@gmail.com wrote:

From: Ye Guojin 

coccicheck complains about the use of snprintf() in sysfs show
functions:
WARNING  use scnprintf or sprintf

Use sysfs_emit instead of scnprintf or sprintf makes more sense.

Reported-by: Zeal Robot 
Signed-off-by: Ye Guojin 
---
drivers/block/virtio_blk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)


Reviewed-by: Stefano Garzarella 

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Re: [PATCH] virtio-blk: fixup coccinelle warnings

[Joe Perches]

On Thu, 2021-10-21 at 06:51 +, cgel@gmail.com wrote:
> From: Ye Guojin 
> 
> coccicheck complains about the use of snprintf() in sysfs show
> functions:
> WARNING  use scnprintf or sprintf
> 
> Use sysfs_emit instead of scnprintf or sprintf makes more sense.
[]
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
[]
> @@ -624,7 +624,7 @@ cache_type_show(struct device *dev, struct 
> device_attribute *attr, char *buf)
> - return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
> + return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]);

Perhaps scripts/coccinelle/api/device_attr_show.cocci should be updated
to be more like the script used in commit 1c7fd72687d6

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
return
-   sprintf(buf,
+   sysfs_emit(buf,
...);
...>
}

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
return
-   snprintf(buf, PAGE_SIZE,
+   sysfs_emit(buf,
...);
...>
}

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
return
-   scnprintf(buf, PAGE_SIZE,
+   sysfs_emit(buf,
...);
...>
}

@@
identifier d_show;
identifier dev, attr, buf;
expression chr;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
return
-   strcpy(buf, chr);
+   sysfs_emit(buf, chr);
...>
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
len =
-   sprintf(buf,
+   sysfs_emit(buf,
...);
...>
return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
len =
-   snprintf(buf, PAGE_SIZE,
+   sysfs_emit(buf,
...);
...>
return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
len =
-   scnprintf(buf, PAGE_SIZE,
+   sysfs_emit(buf,
...);
...>
return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
-   len += scnprintf(buf + len, PAGE_SIZE - len,
+   len += sysfs_emit_at(buf, len,
...);
...>
return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
expression chr;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
...
-   strcpy(buf, chr);
-   return strlen(buf);
+   return sysfs_emit(buf, chr);
}


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Re: [PATCH] virtio-blk: fixup coccinelle warnings

[Stefan Hajnoczi]

On Thu, Oct 21, 2021 at 12:08:23AM -0700, Joe Perches wrote:
> On Thu, 2021-10-21 at 06:51 +, cgel@gmail.com wrote:
> > From: Ye Guojin 
> > 
> > coccicheck complains about the use of snprintf() in sysfs show
> > functions:
> > WARNING  use scnprintf or sprintf
> > 
> > Use sysfs_emit instead of scnprintf or sprintf makes more sense.
> []
> > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> []
> > @@ -624,7 +624,7 @@ cache_type_show(struct device *dev, struct 
> > device_attribute *attr, char *buf)
> > -   return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
> > +   return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]);
> 
> Perhaps scripts/coccinelle/api/device_attr_show.cocci should be updated
> to be more like the script used in commit 1c7fd72687d6

This won't catch the case covered by the patch because it's
"snprintf(buf, 40" instead of "snprintf(buf, PAGE_SIZE", although
any size that's not PAGE_SIZE needs to be reviewed carefully in case the
intent of the statement is to truncate the output.

Stefan


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Re: [PATCH] virtio-blk: fixup coccinelle warnings

[Stefan Hajnoczi]

On Thu, Oct 21, 2021 at 06:51:11AM +, cgel@gmail.com wrote:
> From: Ye Guojin 
> 
> coccicheck complains about the use of snprintf() in sysfs show
> functions:
> WARNING  use scnprintf or sprintf
> 
> Use sysfs_emit instead of scnprintf or sprintf makes more sense.
> 
> Reported-by: Zeal Robot 
> Signed-off-by: Ye Guojin 
> ---
>  drivers/block/virtio_blk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Stefan Hajnoczi 


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