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 1f0f97c..822d241 100644 (file)
--- 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;