[S390] dasd: use vmalloc for statistics input buffer

The size of the buffer that is used to store DASD statistics input
strings depends on the user input. If the input string is to large,
the write operation could fail with -ENOMEM. To avoid this, use
vmalloc instead of kmalloc.
Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

drivers/s390/block/dasd.c

@@ -24,6 +24,7 @@
 #include <linux/mutex.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
+#include <linux/vmalloc.h>
 
 #include <asm/ccwdev.h>
 #include <asm/ebcdic.h>
@@ -888,11 +889,11 @@ char *dasd_get_user_string(const char __user *user_buf, size_t user_len)
 {
 	char *buffer;
 
-	buffer = kmalloc(user_len + 1, GFP_KERNEL);
+	buffer = vmalloc(user_len + 1);
 	if (buffer == NULL)
 		return ERR_PTR(-ENOMEM);
 	if (copy_from_user(buffer, user_buf, user_len) != 0) {
-		kfree(buffer);
+		vfree(buffer);
 		return ERR_PTR(-EFAULT);
 	}
 	/* got the string, now strip linefeed. */
@@ -930,7 +931,7 @@ static ssize_t dasd_stats_write(struct file *file,
 		dasd_profile_off(prof);
 	} else
 		rc = -EINVAL;
-	kfree(buffer);
+	vfree(buffer);
 	return rc;
 }
 
@@ -1042,7 +1043,7 @@ static ssize_t dasd_stats_global_write(struct file *file,
 		dasd_global_profile_level = DASD_PROFILE_OFF;
 	} else
 		rc = -EINVAL;
-	kfree(buffer);
+	vfree(buffer);
 	return rc;
 }
 

drivers/s390/block/dasd_proc.c

@@ -312,14 +312,14 @@ static ssize_t dasd_stats_proc_write(struct file *file,
 		pr_info("The statistics have been reset\n");
 	} else
 		goto out_parse_error;
-	kfree(buffer);
+	vfree(buffer);
 	return user_len;
 out_parse_error:
 	rc = -EINVAL;
 	pr_warning("%s is not a supported value for /proc/dasd/statistics\n",
 		str);
 out_error:
-	kfree(buffer);
+	vfree(buffer);
 	return rc;
 #else
 	pr_warning("/proc/dasd/statistics: is not activated in this kernel\n");