The patch titled
Subject: sysctl: fix int -> unsigned long assignments in INT_MIN case
has been added to the -mm tree. Its filename is
sysctl-fix-int-unsigned-long-assignments-in-int_min-case.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/sysctl-fix-int-unsigned-long-assignments-in-int_min-case.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/sysctl-fix-int-unsigned-long-assignments-in-int_min-case.patch
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------------------------------------------------------
From: Ilya Dryomov <idryomov@xxxxxxxxx>
Subject: 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@xxxxxxxxx>
Cc: Mikulas Patocka <mikulas@xxxxxxxxxxxxx>
Cc: Robert Xiao <nneonneo@xxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sysctl.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff -puN kernel/sysctl.c~sysctl-fix-int-unsigned-long-assignments-in-int_min-case kernel/sysctl.c
--- a/kernel/sysctl.c~sysctl-fix-int-unsigned-long-assignments-in-int_min-case
+++ a/kernel/sysctl.c
@@ -1995,7 +1995,7 @@ static int do_proc_dointvec_conv(bool *n
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(
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
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_jiffi
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_c
unsigned long lval;
if (val < 0) {
*negp = true;
- lval = (unsigned long)-val;
+ lval = -(unsigned long)val;
} else {
*negp = false;
lval = (unsigned long)val;
_
Patches currently in -mm which might be from idryomov@xxxxxxxxx are
sysctl-fix-int-unsigned-long-assignments-in-int_min-case.patch
linux-next.patch
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