be extra careful to not divide by zero; more arches to come

2 files changed, 26 insertions, 3 deletions

diff --git a/sys/arch/alpha/alpha/disksubr.c b/sys/arch/alpha/alpha/disksubr.c
index 0c247eb559d..36219e12429 100644
--- a/sys/arch/alpha/alpha/disksubr.c
+++ b/sys/arch/alpha/alpha/disksubr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: disksubr.c,v 1.26 1998/11/23 03:35:56 millert Exp $	*/
+/*	$OpenBSD: disksubr.c,v 1.27 1999/01/05 04:29:03 millert Exp $	*/
 /*	$NetBSD: disksubr.c,v 1.21 1996/05/03 19:42:03 christos Exp $	*/
 
 /*
@@ -343,6 +343,15 @@ readdoslabel(bp, strat, lp, osdep, partoffp, cylp, spoofonly)
 	int dospartoff, cyl, i, ourpart = -1;
 	dev_t dev;
 
+	if (lp->d_secpercyl == 0) {
+		msg = "invalid label, d_secpercyl == 0";
+		return (msg);
+	}
+	if (lp->d_secsize == 0) {
+		msg = "invalid label, d_secsize == 0";
+		return (msg);
+	}
+
 	/* do dos partitions in the process of getting disklabel? */
 	dospartoff = 0;
 	cyl = I386_LABELSECTOR / lp->d_secpercyl;
@@ -745,6 +754,13 @@ bounds_check_with_label(bp, lp, osdep, wlabel)
 	    lp) + osdep->labelsector;
 	int sz = howmany(bp->b_bcount, DEV_BSIZE);
 
+	/* avoid division by zero */
+	if (lp->d_secpercyl == 0) {
+		bp->b_error = EINVAL;
+		goto bad;
+	}
+
+	/* beyond partition? */
 	if (bp->b_blkno + sz > blockpersec(p->p_size, lp)) {
 		sz = blockpersec(p->p_size, lp) - bp->b_blkno;
 		if (sz == 0) {
diff --git a/sys/arch/sparc/sparc/disksubr.c b/sys/arch/sparc/sparc/disksubr.c
index 3de46d07cc5..1b5c134a8c0 100644
--- a/sys/arch/sparc/sparc/disksubr.c
+++ b/sys/arch/sparc/sparc/disksubr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: disksubr.c,v 1.21 1998/10/03 21:18:56 millert Exp $	*/
+/*	$OpenBSD: disksubr.c,v 1.22 1999/01/05 04:29:03 millert Exp $	*/
 /*	$NetBSD: disksubr.c,v 1.16 1996/04/28 20:25:59 thorpej Exp $ */
 
 /*
@@ -318,6 +318,12 @@ bounds_check_with_label(bp, lp, osdep, wlabel)
 		goto bad;
 	}
 
+	/* avoid division by zero */
+	if (lp->d_secpercyl == 0) {
+		bp->b_error = EINVAL;
+		goto bad;
+	}
+
 	/* beyond partition? */
 	if (bp->b_blkno + sz > blockpersec(p->p_size, lp)) {
 		sz = blockpersec(p->p_size, lp) - bp->b_blkno;
@@ -521,7 +527,8 @@ disklabel_bsd_to_sun(lp, cp)
 	int i, secpercyl;
 	u_short cksum, *sp1, *sp2;
 
-	if (lp->d_secsize != 512)
+	/* Enforce preconditions */
+	if (lp->d_secsize != 512 || lp->d_nsectors == 0 || lp->d_ntracks == 0)
 		return (EINVAL);
 
 	sl = (struct sun_disklabel *)cp;