Relax GTP header validity check by allowing 1 sector size usable

LBA area (gh_lba_start == gh_lba_end) and allowing either or both
of gh_lba_start and gh_lba_end to exceed the size of the disk the
GPT currently inhabits.

Reduces false negatives and inappropriate fall through to MBR
spoofing and allows repair of otherwise valid GPT.

diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index 94a6792..cac0b45 100644 (file)
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: subr_disk.c,v 1.255 2022/09/01 13:45:27 krw Exp $     */
+/*     $OpenBSD: subr_disk.c,v 1.256 2022/09/02 12:24:26 krw Exp $     */
 /*     $NetBSD: subr_disk.c,v 1.17 1996/03/16 23:17:08 christos Exp $  */
 
 /*
@@ -484,8 +484,7 @@ gpt_get_hdr(struct buf *bp, void (*strat)(struct buf *), struct disklabel *lp,
 
        if (letoh64(ngh.gh_sig) == GPTSIGNATURE &&
            letoh32(ngh.gh_rev) == GPTREVISION &&
-           size == GPTMINHDRSIZE && lbastart < lbaend &&
-           lbastart < DL_GETDSIZE(lp) && lbaend < DL_GETDSIZE(lp) &&
+           size == GPTMINHDRSIZE && lbastart <= lbaend &&
            partsize == GPTMINPARTSIZE && lp->d_secsize % partsize == 0 &&
            csum == ngh.gh_csum)
                *gh = ngh;