From 81d2f9166a86513892803d07ac9b0df4a5b965bb Mon Sep 17 00:00:00 2001
From: miod <miod@openbsd.org>
Date: Sun, 11 Sep 2022 19:34:40 +0000
Subject: [PATCH] Remove the DKF_LABELVALID flag from struct disk. Instead,
 trust disk drivers to always be able to provide a duid, and keep ignoring
 whole zero duids.

This fixes a race in vnd setup where the disk_attach callback could run
before any I/O occurs on the vnd, thus not having a label available yet.

noticed by otto@ and kn@; ok kn@
---
 sys/dev/softraid.c   |  6 ++----
 sys/kern/subr_disk.c | 13 ++++++-------
 sys/sys/disk.h       |  3 +--
 3 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/sys/dev/softraid.c b/sys/dev/softraid.c
index ebf092a40e5..b243dd3a931 100644
--- a/sys/dev/softraid.c
+++ b/sys/dev/softraid.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: softraid.c,v 1.426 2022/08/29 19:01:52 stsp Exp $ */
+/* $OpenBSD: softraid.c,v 1.427 2022/09/11 19:34:40 miod Exp $ */
 /*
  * Copyright (c) 2007, 2008, 2009 Marco Peereboom <marco@peereboom.us>
  * Copyright (c) 2008 Chris Kuethe <ckuethe@openbsd.org>
@@ -3690,13 +3690,11 @@ sr_ioctl_installboot(struct sr_softc *sc, struct sr_discipline *sd,
 		}
 	}
 
-	bzero(duid, sizeof(duid));
 	TAILQ_FOREACH(dk, &disklist,  dk_link)
 		if (!strncmp(dk->dk_name, bb->bb_dev, sizeof(bb->bb_dev)))
 			break;
 	if (dk == NULL || dk->dk_label == NULL ||
-	    (dk->dk_flags & DKF_LABELVALID) == 0 ||
-	    bcmp(dk->dk_label->d_uid, &duid, sizeof(duid)) == 0) {
+	    duid_iszero(dk->dk_label->d_uid)) {
 		sr_error(sc, "failed to get DUID for softraid volume");
 		goto done;
 	}
diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index 6623dd816bc..a387fdc5529 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_disk.c,v 1.261 2022/09/11 11:47:55 krw Exp $	*/
+/*	$OpenBSD: subr_disk.c,v 1.262 2022/09/11 19:34:40 miod Exp $	*/
 /*	$NetBSD: subr_disk.c,v 1.17 1996/03/16 23:17:08 christos Exp $	*/
 
 /*
@@ -1130,7 +1130,6 @@ disk_attach_callback(void *xdat)
 	/* Read disklabel. */
 	if (disk_readlabel(&dl, dk->dk_devno, errbuf, sizeof(errbuf)) == NULL) {
 		enqueue_randomness(dl.d_checksum);
-		dk->dk_flags |= DKF_LABELVALID;
 	}
 
 done:
@@ -1449,14 +1448,14 @@ setroot(struct device *bootdv, int part, int exitflags)
 		TAILQ_FOREACH(dk, &disklist, dk_link)
 			if (dk->dk_device == bootdv)
 				break;
-		if (dk && (dk->dk_flags & DKF_LABELVALID))
+		if (dk)
 			bcopy(dk->dk_label->d_uid, bootduid, sizeof(bootduid));
 	} else if (bootdv == NULL) {
 		/* Locate boot disk based on the provided DUID. */
 		TAILQ_FOREACH(dk, &disklist, dk_link)
 			if (duid_equal(dk->dk_label->d_uid, bootduid))
 				break;
-		if (dk && (dk->dk_flags & DKF_LABELVALID))
+		if (dk)
 			bootdv = dk->dk_device;
 	}
 	bcopy(bootduid, rootduid, sizeof(rootduid));
@@ -1570,8 +1569,7 @@ gotswap:
 		if (bootdv->dv_class == DV_DISK) {
 			if (!duid_iszero(rootduid)) {
 				TAILQ_FOREACH(dk, &disklist, dk_link)
-					if ((dk->dk_flags & DKF_LABELVALID) &&
-					    dk->dk_label && duid_equal(
+					if (dk->dk_label && duid_equal(
 					    dk->dk_label->d_uid, rootduid))
 						break;
 				if (dk == NULL)
@@ -1797,7 +1795,8 @@ disk_map(char *path, char *mappath, int size, int flags)
 
 	mdk = NULL;
 	TAILQ_FOREACH(dk, &disklist, dk_link) {
-		if ((dk->dk_flags & DKF_LABELVALID) && dk->dk_label &&
+		if (dk->dk_label &&
+		    !duid_iszero(dk->dk_label->d_uid) &&
 		    memcmp(dk->dk_label->d_uid, uid,
 		    sizeof(dk->dk_label->d_uid)) == 0) {
 			/* Fail if there are duplicate UIDs! */
diff --git a/sys/sys/disk.h b/sys/sys/disk.h
index 4dcd48839f0..a024bb1c4a7 100644
--- a/sys/sys/disk.h
+++ b/sys/sys/disk.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: disk.h,v 1.36 2017/05/04 22:47:27 deraadt Exp $	*/
+/*	$OpenBSD: disk.h,v 1.37 2022/09/11 19:34:40 miod Exp $	*/
 /*	$NetBSD: disk.h,v 1.11 1996/04/28 20:22:50 thorpej Exp $	*/
 
 /*
@@ -83,7 +83,6 @@ struct disk {
 #define DKF_CONSTRUCTED	0x0001
 #define DKF_OPENED	0x0002
 #define DKF_NOLABELREAD	0x0004
-#define DKF_LABELVALID	0x0008
 
 	/*
 	 * Metrics data; note that some metrics may have no meaning
-- 
2.20.1