From: krw <krw@openbsd.org>
Date: Sat, 20 Aug 2022 13:10:45 +0000 (+0000)
Subject: Restore the exemption from start/size checks that OpenBSD (A6)
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=1b10218152059da8b8d9dcbf6ba86e3c64ab5bf0;p=openbsd

Restore the exemption from start/size checks that OpenBSD (A6)
MBR partitions previously enjoyed.

Found and fix tested by matthieu@
---

diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index 1f0f97ca3bc..822d2415b14 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_disk.c,v 1.253 2022/08/14 01:58:27 jsg Exp $	*/
+/*	$OpenBSD: subr_disk.c,v 1.254 2022/08/20 13:10:45 krw Exp $	*/
 /*	$NetBSD: subr_disk.c,v 1.17 1996/03/16 23:17:08 christos Exp $	*/
 
 /*
@@ -740,12 +740,17 @@ spoofmbr(struct buf *bp, void (*strat)(struct buf *), const uint8_t *dosbb,
 		}
 
 		for (i = 0; i < NDOSPART; i++) {
-			if (letoh32(dp[i].dp_start) > DL_GETDSIZE(lp))
-				continue;
-			if (letoh32(dp[i].dp_size) > DL_GETDSIZE(lp))
-				continue;
 			if (letoh32(dp[i].dp_size) == 0)
 				continue;
+			if (obsdfound && dp[i].dp_typ == DOSPTYP_OPENBSD)
+				continue;
+
+			if (dp[i].dp_typ != DOSPTYP_OPENBSD) {
+				if (letoh32(dp[i].dp_start) > DL_GETDSIZE(lp))
+					continue;
+				if (letoh32(dp[i].dp_size) > DL_GETDSIZE(lp))
+					continue;
+			}
 
 			start = sector + letoh32(dp[i].dp_start);
 			end = start + letoh32(dp[i].dp_size);
@@ -760,15 +765,13 @@ spoofmbr(struct buf *bp, void (*strat)(struct buf *), const uint8_t *dosbb,
 
 			switch (dp[i].dp_typ) {
 			case DOSPTYP_OPENBSD:
-				if (obsdfound == 0) {
-					obsdfound = 1;
-					partoff = DL_SECTOBLK(lp, start);
-					labeloff = partoff + DOS_LABELSECTOR;
-					if (labeloff >= DL_SECTOBLK(lp, end))
-						partoff = -1;
-					DL_SETBSTART(lp, start);
-					DL_SETBEND(lp, end);
-				}
+				obsdfound = 1;
+				partoff = DL_SECTOBLK(lp, start);
+				labeloff = partoff + DOS_LABELSECTOR;
+				if (labeloff >= DL_SECTOBLK(lp, end))
+					partoff = -1;
+				DL_SETBSTART(lp, start);
+				DL_SETBEND(lp, end);
 				continue;
 			case DOSPTYP_EFI:
 				continue;