From: krw <krw@openbsd.org>
Date: Mon, 25 Aug 2008 11:27:00 +0000 (+0000)
Subject: If partoffp is non-NULL then readdoslabel() is just looking for the
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=a41642971dfc8a4865f478960586a4a706406bd0;p=openbsd

If partoffp is non-NULL then readdoslabel() is just looking for the
correct address to write the passed label. Don't spoof partitions
while looking for the address, as this could result in an invalid
label being written out.

"That looks right" deraadt@ "Looks good to me" miod@
---

diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index cb0d89338fd..5668686cb31 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_disk.c,v 1.81 2008/08/22 03:19:02 deraadt Exp $	*/
+/*	$OpenBSD: subr_disk.c,v 1.82 2008/08/25 11:27:00 krw Exp $	*/
 /*	$NetBSD: subr_disk.c,v 1.17 1996/03/16 23:17:08 christos Exp $	*/
 
 /*
@@ -447,6 +447,7 @@ donot:
 		 */
 		for (dp2=dp, i=0; i < NDOSPART && n < 8; i++, dp2++) {
 			struct partition *pp = &lp->d_partitions[8+n];
+			u_int8_t fstype;
 
 			if (dp2->dp_typ == DOSPTYP_OPENBSD)
 				continue;
@@ -459,17 +460,17 @@ donot:
 
 			switch (dp2->dp_typ) {
 			case DOSPTYP_UNUSED:
-				pp->p_fstype = FS_UNUSED;
+				fstype = FS_UNUSED;
 				n++;
 				break;
 
 			case DOSPTYP_LINUX:
-				pp->p_fstype = FS_EXT2FS;
+				fstype = FS_EXT2FS;
 				n++;
 				break;
 
 			case DOSPTYP_NTFS:
-				pp->p_fstype = FS_NTFS;
+				fstype = FS_NTFS;
 				n++;
 				break;
 
@@ -479,7 +480,7 @@ donot:
 			case DOSPTYP_FAT16L:
 			case DOSPTYP_FAT32:
 			case DOSPTYP_FAT32L:
-				pp->p_fstype = FS_MSDOS;
+				fstype = FS_MSDOS;
 				n++;
 				break;
 			case DOSPTYP_EXTEND:
@@ -492,25 +493,30 @@ donot:
 				wander = 1;
 				break;
 			default:
-				pp->p_fstype = FS_OTHER;
+				fstype = FS_OTHER;
 				n++;
 				break;
 			}
 
 			/*
-			 * There is no need to set the offset/size when
-			 * wandering; it would also invalidate the
-			 * disklabel checksum.
+			 * Don't set fstype/offset/size when wandering or just
+			 * looking for the offset of the OpenBSD partition. It
+			 * would invalidate the disklabel checksum!
 			 */
-			if (wander)
+			if (wander || partoffp)
 				continue;
 
+			pp->p_fstype = fstype;
 			if (letoh32(dp2->dp_start))
 				DL_SETPOFFSET(pp,
 				    letoh32(dp2->dp_start) + part_blkno);
 			DL_SETPSIZE(pp, letoh32(dp2->dp_size));
 		}
 	}
+	if (partoffp)
+		/* dospartoff has been set and we must not modify *lp. */
+		goto notfat;
+
 	lp->d_npartitions = MAXPARTITIONS;
 
 	if (n == 0 && part_blkno == DOSBBSECTOR) {