[src/trunk]: src/sys/dev Appease toxic bullshit warning from gcc.

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

details:   https://anonhg.NetBSD.org/src/rev/e07984e13ccf
branches:  trunk
changeset: 825713:e07984e13ccf
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Fri Jul 28 16:30:41 2017 +0000

description:
Appease toxic bullshit warning from gcc.

If you have a better way to write a useful bounds check that happens
to always pass on LP64 but doesn't always on LP32, without making it
fail to compile on LP64 or making it an #ifdef conditional on LP32,
please put it in here instead.

diffstat:

 sys/dev/vnd.c |  21 ++++++++++++++++-----
 1 files changed, 16 insertions(+), 5 deletions(-)

diffs (42 lines):

diff -r e494c2be3382 -r e07984e13ccf sys/dev/vnd.c
--- a/sys/dev/vnd.c     Fri Jul 28 16:22:01 2017 +0000
+++ b/sys/dev/vnd.c     Fri Jul 28 16:30:41 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vnd.c,v 1.261 2017/07/28 16:22:01 riastradh Exp $      */
+/*     $NetBSD: vnd.c,v 1.262 2017/07/28 16:30:41 riastradh Exp $      */
 
 /*-
  * Copyright (c) 1996, 1997, 1998, 2008 The NetBSD Foundation, Inc.
@@ -91,7 +91,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.261 2017/07/28 16:22:01 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.262 2017/07/28 16:30:41 riastradh Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_vnd.h"
@@ -1303,9 +1303,20 @@
                        }
                        KASSERT(0 < vnd->sc_comp_blksz);
                        KASSERT(0 < vnd->sc_comp_numoffs);
-                       if ((SIZE_MAX/sizeof(uint64_t) <
-                               vnd->sc_comp_numoffs) ||
-                           (vattr.va_size < sizeof(struct vnd_comp_header)) ||
+                       /*
+                        * @#^@!$& gcc -Wtype-limits refuses to let me
+                        * write SIZE_MAX/sizeof(uint64_t) < numoffs,
+                        * because the range of the type on amd64 makes
+                        * the comparisons always false.
+                        */
+#if SIZE_MAX <= UINT32_MAX*(64/CHAR_BIT)
+                       if (SIZE_MAX/sizeof(uint64_t) < vnd->sc_comp_numoffs) {
+                               VOP_UNLOCK(nd.ni_vp);
+                               error = EINVAL;
+                               goto close_and_exit;
+                       }
+#endif
+                       if ((vattr.va_size < sizeof(struct vnd_comp_header)) ||
                            (vattr.va_size - sizeof(struct vnd_comp_header) <
                                sizeof(uint64_t)*vnd->sc_comp_numoffs) ||
                            (UQUAD_MAX/vnd->sc_comp_blksz <