sysfs: sysfs_write_file() writes zero terminated data

since most of the files in sysfs are text files,
it would be nice, if the "store" function called
during sysfs_write_file() gets a zero terminated
string / data.
The current implementation seems not to ensure this.
(But only if it is the first time the zeroed buffer
page is allocated.)

So the buffer can be scanned by sscanf() easily,
for example.

This patch simply sets a \0 char behind the
data in buffer->page.
Signed-off-by: Thomas Maier <balagi@justmail.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/file.c

@@ -190,6 +190,9 @@ fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t
 		count = PAGE_SIZE - 1;
 	error = copy_from_user(buffer->page,buf,count);
 	buffer->needs_read_fill = 1;
+	/* if buf is assumed to contain a string, terminate it by \0,
+	   so e.g. sscanf() can scan the string easily */
+	buffer->page[count] = 0;
 	return error ? -EFAULT : count;
 }