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authorIlya Dryomov <idryomov@gmail.com>2015-09-09 15:39:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-10 13:29:01 -0700
commit9a5bc726d559221a3394bb8ef97d0abc1ee94d00 (patch)
tree8d6bcc02409b4754e9641488b03599b28af8e6e4 /kernel/sysctl.c
parent1303a27c9c32020a3b6ac89be270d2ab1f28be24 (diff)
downloadlinux-sh-9a5bc726d559221a3394bb8ef97d0abc1ee94d00.tar.gz
sysctl: fix int -> unsigned long assignments in INT_MIN case
The following if (val < 0) *lvalp = (unsigned long)-val; is incorrect because the compiler is free to assume -val to be positive and use a sign-extend instruction for extending the bit pattern. This is a problem if val == INT_MIN: # echo -2147483648 >/proc/sys/dev/scsi/logging_level # cat /proc/sys/dev/scsi/logging_level -18446744071562067968 Cast to unsigned long before negation - that way we first sign-extend and then negate an unsigned, which is well defined. With this: # cat /proc/sys/dev/scsi/logging_level -2147483648 Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Cc: Mikulas Patocka <mikulas@twibright.com> Cc: Robert Xiao <nneonneo@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r--kernel/sysctl.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 715cc57cc66a..e69201d8094e 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1995,7 +1995,7 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
int val = *valp;
if (val < 0) {
*negp = true;
- *lvalp = (unsigned long)-val;
+ *lvalp = -(unsigned long)val;
} else {
*negp = false;
*lvalp = (unsigned long)val;
@@ -2201,7 +2201,7 @@ static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
int val = *valp;
if (val < 0) {
*negp = true;
- *lvalp = (unsigned long)-val;
+ *lvalp = -(unsigned long)val;
} else {
*negp = false;
*lvalp = (unsigned long)val;
@@ -2436,7 +2436,7 @@ static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp,
unsigned long lval;
if (val < 0) {
*negp = true;
- lval = (unsigned long)-val;
+ lval = -(unsigned long)val;
} else {
*negp = false;
lval = (unsigned long)val;
@@ -2459,7 +2459,7 @@ static int do_proc_dointvec_userhz_jiffies_conv(bool *negp, unsigned long *lvalp
unsigned long lval;
if (val < 0) {
*negp = true;
- lval = (unsigned long)-val;
+ lval = -(unsigned long)val;
} else {
*negp = false;
lval = (unsigned long)val;
@@ -2484,7 +2484,7 @@ static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp,
unsigned long lval;
if (val < 0) {
*negp = true;
- lval = (unsigned long)-val;
+ lval = -(unsigned long)val;
} else {
*negp = false;
lval = (unsigned long)val;