Re: [PATCH] watchdog: Use sysfs_emit() and sysfs_emit_at() in "show" functions

On Wed, 12 May 2021 21:48:37 -0700
Joe Perches [off-list ref] wrote:

On Tue, 2021-05-11 at 08:18 +0200, Juerg Haefliger wrote:

quoted

Convert sprintf() in sysfs "show" functions to sysfs_emit() and
sysfs_emit_at() in order to check for buffer overruns in sysfs outputs.  

[]

quoted

diff --git a/drivers/watchdog/ziirave_wdt.c b/drivers/watchdog/ziirave_wdt.c  

[]

quoted

@@ -445,8 +445,9 @@ static ssize_t ziirave_wdt_sysfs_show_firm(struct device *dev,

 	if (ret)
 		return ret;
 

-	ret = sprintf(buf, ZIIRAVE_FW_VERSION_FMT, w_priv->firmware_rev.major,
-		      w_priv->firmware_rev.minor);
+	ret = sysfs_emit(buf, ZIIRAVE_FW_VERSION_FMT,
+			 w_priv->firmware_rev.major,
+			 w_priv->firmware_rev.minor);
 

 	mutex_unlock(&w_priv->sysfs_mutex);
 

@@ -468,8 +469,9 @@ static ssize_t ziirave_wdt_sysfs_show_boot(struct device *dev,

 	if (ret)
 		return ret;
 

-	ret = sprintf(buf, ZIIRAVE_BL_VERSION_FMT, w_priv->bootloader_rev.major,
-		      w_priv->bootloader_rev.minor);
+	ret = sysfs_emit(buf, ZIIRAVE_BL_VERSION_FMT,
+			 w_priv->bootloader_rev.major,
+			 w_priv->bootloader_rev.minor);
 

 	mutex_unlock(&w_priv->sysfs_mutex);
 

@@ -491,7 +493,7 @@ static ssize_t ziirave_wdt_sysfs_show_reason(struct device *dev,

 	if (ret)
 		return ret;
 

-	ret = sprintf(buf, "%s", ziirave_reasons[w_priv->reset_reason]);
+	ret = sysfs_emit(buf, "%s", ziirave_reasons[w_priv->reset_reason]);  

All of these formats should probably end with a newline
and the ZIIRAVE_<FOO>_VERSION_FMT defines are to me unnecessary.

I'll send a follow-on patch for that.

...Juerg