[src/trunk]: src/sys/kern autoconf(9): Refuse to consider negative unit numbe...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/14273617912c
branches:  trunk
changeset: 363449:14273617912c
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Mar 12 19:26:33 2022 +0000

description:
autoconf(9): Refuse to consider negative unit numbers in cfdata.

Reported-by: syzbot+a63ae6c58df86f40b6f3%syzkaller.appspotmail.com@localhost

diffstat:

 sys/kern/subr_autoconf.c |  13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diffs (42 lines):

diff -r cb5b9c755080 -r 14273617912c sys/kern/subr_autoconf.c
--- a/sys/kern/subr_autoconf.c  Sat Mar 12 18:31:39 2022 +0000
+++ b/sys/kern/subr_autoconf.c  Sat Mar 12 19:26:33 2022 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_autoconf.c,v 1.295 2022/02/06 19:29:52 tnn Exp $ */
+/* $NetBSD: subr_autoconf.c,v 1.296 2022/03/12 19:26:33 riastradh Exp $ */
 
 /*
  * Copyright (c) 1996, 2000 Christopher G. Demetriou
@@ -77,7 +77,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.295 2022/02/06 19:29:52 tnn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.296 2022/03/12 19:26:33 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
@@ -1473,10 +1473,12 @@
 static int
 config_unit_nextfree(cfdriver_t cd, cfdata_t cf)
 {
-       int unit;
-
+       int unit = cf->cf_unit;
+
+       if (unit < 0)
+               return -1;
        if (cf->cf_fstate == FSTATE_STAR) {
-               for (unit = cf->cf_unit; unit < cd->cd_ndevs; unit++)
+               for (; unit < cd->cd_ndevs; unit++)
                        if (cd->cd_devs[unit] == NULL)
                                break;
                /*
@@ -1484,7 +1486,6 @@
                 * or max(cd->cd_ndevs,cf->cf_unit).
                 */
        } else {
-               unit = cf->cf_unit;
                if (unit < cd->cd_ndevs && cd->cd_devs[unit] != NULL)
                        unit = -1;
        }