[src/trunk]: src/sys/dev It is not sufficient to have a comment /* Sanity che...

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

details:   https://anonhg.NetBSD.org/src/rev/cad9a1eaf735
branches:  trunk
changeset: 373015:cad9a1eaf735
user:      hannken <hannken%NetBSD.org@localhost>
date:      Fri Jan 13 15:46:40 2023 +0000

description:
It is not sufficient to have a comment /* Sanity check the size. */,
also check the size is greater than zero and a multiple of DEV_BSIZE.

Reported-by: syzbot+318187e5124846542f8d%syzkaller.appspotmail.com@localhost

diffstat:

 sys/dev/md.c |  11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diffs (34 lines):

diff -r 5b16cac6049c -r cad9a1eaf735 sys/dev/md.c
--- a/sys/dev/md.c      Thu Jan 12 19:17:11 2023 +0000
+++ b/sys/dev/md.c      Fri Jan 13 15:46:40 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: md.c,v 1.86 2022/09/24 23:20:13 thorpej Exp $  */
+/*     $NetBSD: md.c,v 1.87 2023/01/13 15:46:40 hannken Exp $  */
 
 /*
  * Copyright (c) 1995 Gordon W. Ross, Leo Weppelman.
@@ -40,7 +40,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: md.c,v 1.86 2022/09/24 23:20:13 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: md.c,v 1.87 2023/01/13 15:46:40 hannken Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_md.h"
@@ -589,10 +589,13 @@
        vaddr_t addr;
        vsize_t size;
 
+       /* Sanity check the size. */
+       size = umd->md_size;
+       if (size < DEV_BSIZE || (size % DEV_BSIZE) != 0)
+               return EINVAL;
+
        mutex_exit(&sc->sc_lock);
 
-       /* Sanity check the size. */
-       size = umd->md_size;
        addr = uvm_km_alloc(kernel_map, size, 0, UVM_KMF_WIRED|UVM_KMF_ZERO);
 
        mutex_enter(&sc->sc_lock);