X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=kernel%2Fdrivers%2Fs390%2Fchar%2Fkeyboard.c;h=ef04a9f7a70494bea94032b7b4eb896eb11553a7;hb=e09b41010ba33a20a87472ee821fa407a5b8da36;hp=01463b052ae740aa56cd6ea816102a34961ed668;hpb=f93b97fd65072de626c074dbe099a1fff05ce060;p=kvmfornfv.git

diff --git a/kernel/drivers/s390/char/keyboard.c b/kernel/drivers/s390/char/keyboard.c
index 01463b052..ef04a9f7a 100644
--- a/kernel/drivers/s390/char/keyboard.c
+++ b/kernel/drivers/s390/char/keyboard.c
@@ -433,20 +433,23 @@ do_kdgkb_ioctl(struct kbd_data *kbd, struct kbsentry __user *u_kbs,
 	case KDSKBSENT:
 		if (!perm)
 			return -EPERM;
-		len = strnlen_user(u_kbs->kb_string,
-				   sizeof(u_kbs->kb_string) - 1);
+		len = strnlen_user(u_kbs->kb_string, sizeof(u_kbs->kb_string));
 		if (!len)
 			return -EFAULT;
-		if (len > sizeof(u_kbs->kb_string) - 1)
+		if (len > sizeof(u_kbs->kb_string))
 			return -EINVAL;
-		p = kmalloc(len + 1, GFP_KERNEL);
+		p = kmalloc(len, GFP_KERNEL);
 		if (!p)
 			return -ENOMEM;
 		if (copy_from_user(p, u_kbs->kb_string, len)) {
 			kfree(p);
 			return -EFAULT;
 		}
-		p[len] = 0;
+		/*
+		 * Make sure the string is terminated by 0. User could have
+		 * modified it between us running strnlen_user() and copying it.
+		 */
+		p[len - 1] = 0;
 		kfree(kbd->func_table[kb_func]);
 		kbd->func_table[kb_func] = p;
 		break;