Module Name: src
Committed By: kamil
Date: Wed Jul 25 22:07:59 UTC 2018
Modified Files:
src/sys/fs/msdosfs: msdosfs_fat.c
Log Message:
Avoid undefined behavior semantics in msdosfs_fat.c
Do not change signedness bit with left shift.
While there avoid signed integer overflow.
Address both issues with using unsigned type.
msdosfs_fat.c:512:42, left shift of 1 by 31 places cannot be represented in
type 'int'
msdosfs_fat.c:521:44, left shift of 1 by 31 places cannot be represented in
type 'int'
msdosfs_fat.c:744:14, left shift of 1 by 31 places cannot be represented in
type 'int'
msdosfs_fat.c:744:24, signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int [20]'
msdosfs_fat.c:840:13, left shift of 1 by 31 places cannot be represented in
type 'int'
msdosfs_fat.c:840:36, signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int [20]'
Detected with micro-UBSan in the user mode.
To generate a diff of this commit:
cvs rdiff -u -r1.32 -r1.33 src/sys/fs/msdosfs/msdosfs_fat.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/fs/msdosfs/msdosfs_fat.c
diff -u src/sys/fs/msdosfs/msdosfs_fat.c:1.32 src/sys/fs/msdosfs/msdosfs_fat.c:1.33
--- src/sys/fs/msdosfs/msdosfs_fat.c:1.32 Sat Jan 27 03:54:01 2018
+++ src/sys/fs/msdosfs/msdosfs_fat.c Wed Jul 25 22:07:59 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: msdosfs_fat.c,v 1.32 2018/01/27 03:54:01 sevan Exp $ */
+/* $NetBSD: msdosfs_fat.c,v 1.33 2018/07/25 22:07:59 kamil Exp $ */
/*-
* Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
@@ -52,7 +52,7 @@
#endif
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: msdosfs_fat.c,v 1.32 2018/01/27 03:54:01 sevan Exp $");
+__KERNEL_RCSID(0, "$NetBSD: msdosfs_fat.c,v 1.33 2018/07/25 22:07:59 kamil Exp $");
/*
* kernel include files.
@@ -409,7 +409,7 @@ updatefats(struct msdosfsmount *pmp, str
if (pmp->pm_freeclustercount
&& (pmp->pm_inusemap[cn / N_INUSEBITS]
- & (1 << (cn % N_INUSEBITS)))) {
+ & (1U << (cn % N_INUSEBITS)))) {
/*
* The cluster indicated in FSInfo isn't free
* any longer. Got get a new free one.
@@ -509,7 +509,7 @@ static inline void
usemap_alloc(struct msdosfsmount *pmp, u_long cn)
{
- pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
+ pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
pmp->pm_freeclustercount--;
}
@@ -518,7 +518,7 @@ usemap_free(struct msdosfsmount *pmp, u_
{
pmp->pm_freeclustercount++;
- pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
+ pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS));
}
int
@@ -741,7 +741,7 @@ chainlength(struct msdosfsmount *pmp, u_
idx = start / N_INUSEBITS;
start %= N_INUSEBITS;
map = pmp->pm_inusemap[idx];
- map &= ~((1 << start) - 1);
+ map &= ~((1U << start) - 1);
if (map) {
len = ffs(map) - 1 - start;
return (len > count ? count : len);
@@ -837,7 +837,7 @@ clusteralloc(struct msdosfsmount *pmp, u
for (cn = newst; cn <= pmp->pm_maxcluster;) {
idx = cn / N_INUSEBITS;
map = pmp->pm_inusemap[idx];
- map |= (1 << (cn % N_INUSEBITS)) - 1;
+ map |= (1U << (cn % N_INUSEBITS)) - 1;
if (map != (u_int)-1) {
cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
if ((l = chainlength(pmp, cn, count)) >= count)
@@ -854,7 +854,7 @@ clusteralloc(struct msdosfsmount *pmp, u
for (cn = 0; cn < newst;) {
idx = cn / N_INUSEBITS;
map = pmp->pm_inusemap[idx];
- map |= (1 << (cn % N_INUSEBITS)) - 1;
+ map |= (1U << (cn % N_INUSEBITS)) - 1;
if (map != (u_int)-1) {
cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
if ((l = chainlength(pmp, cn, count)) >= count)
