Print warning when a GPT partition start or end is outside the

usable LBA area of the device the GPT is currently inhabiting.

Makes GPT display as informative as MBR display.

In passing, eliminate possible underflow in partition size
calculation.

ok deraadt@

diff --git a/sbin/fdisk/gpt.c b/sbin/fdisk/gpt.c
index fac7ed8..247c7d2 100644 (file)
--- a/sbin/fdisk/gpt.c
+++ b/sbin/fdisk/gpt.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: gpt.c,v 1.79 2022/06/28 15:35:24 krw Exp $    */
+/*     $OpenBSD: gpt.c,v 1.80 2022/08/29 19:39:10 krw Exp $    */
 /*
  * Copyright (c) 2015 Markus Muller <mmu@grummel.net>
  * Copyright (c) 2015 Kenneth R Westerback <krw@openbsd.org>
@@ -437,15 +437,16 @@ GPT_print_part(const unsigned int pn, const char *units, const int verbosity)
        const struct unit_type  *ut;
        char                    *guidstr = NULL;
        double                   size;
-       uint64_t                 sectors;
+       uint64_t                 end, start;
        uint32_t                 status;
 
-       sectors = gp[pn].gp_lba_end - gp[pn].gp_lba_start + 1;
-       size = units_size(units, sectors, &ut);
+       start = gp[pn].gp_lba_start;
+       end = gp[pn].gp_lba_end;
+       size = units_size(units, (start > end) ? 0 : end - start + 1, &ut);
+
        printf("%c%3u: %-36s [%12lld: %12.0f%s]\n",
            gp[pn].gp_attrs & GPTDOSACTIVE ? '*' : ' ', pn,
-           PRT_uuid_to_sname(&gp[pn].gp_type), gp[pn].gp_lba_start,
-           size, ut->ut_abbr);
+           PRT_uuid_to_sname(&gp[pn].gp_type), start, size, ut->ut_abbr);
 
        if (verbosity == VERBOSE) {
                uuid_to_string(&gp[pn].gp_guid, &guidstr, &status);
@@ -456,6 +457,12 @@ GPT_print_part(const unsigned int pn, const char *units, const int verbosity)
                printf("%-36s\n", name_to_string(pn));
                free(guidstr);
        }
+
+       if (start > end)
+               printf("partition %u first LBA is > last LBA\n", pn);
+       if (start < gh.gh_lba_start || end > gh.gh_lba_end)
+               printf("partition %u extends beyond usable LBA range of %s\n",
+                   pn, disk.dk_name);
 }
 
 int