* [PATCH] sysctl: do not allow a 64bit value write in a 32bit knob
@ 2018-08-27 20:27 Aristeu Rozanski
2018-08-28 4:43 ` kbuild test robot
2018-08-28 7:21 ` kbuild test robot
0 siblings, 2 replies; 3+ messages in thread
From: Aristeu Rozanski @ 2018-08-27 20:27 UTC (permalink / raw)
To: linux-kernel; +Cc: Luis R. Rodriguez, Kees Cook
Writing to a sysctl file that uses proc_dointvec_minmax like user/max_uts_namespaces
a larger than 32 bit value won't cause an error as expected but instead will zero
its value:
# echo 214748364800000 > max_uts_namespaces
# cat max_uts_namespaces
0
This patches fixes it.
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4ac9b9a..243f277 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2486,7 +2486,8 @@ static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
if (write) {
int val = *negp ? -*lvalp : *lvalp;
if ((param->min && *param->min > val) ||
- (param->max && *param->max < val))
+ (param->max && *param->max < val) ||
+ *lvalp >> (sizeof(int) * 8))
return -EINVAL;
*valp = val;
} else {
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] sysctl: do not allow a 64bit value write in a 32bit knob
2018-08-27 20:27 [PATCH] sysctl: do not allow a 64bit value write in a 32bit knob Aristeu Rozanski
@ 2018-08-28 4:43 ` kbuild test robot
2018-08-28 7:21 ` kbuild test robot
1 sibling, 0 replies; 3+ messages in thread
From: kbuild test robot @ 2018-08-28 4:43 UTC (permalink / raw)
To: Aristeu Rozanski; +Cc: kbuild-all, linux-kernel, Luis R. Rodriguez, Kees Cook
[-- Attachment #1: Type: text/plain, Size: 1958 bytes --]
Hi Aristeu,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on v4.19-rc1 next-20180827]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Aristeu-Rozanski/sysctl-do-not-allow-a-64bit-value-write-in-a-32bit-knob/20180828-043801
config: microblaze-mmu_defconfig (attached as .config)
compiler: microblaze-linux-gcc (GCC) 8.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=8.1.0 make.cross ARCH=microblaze
All warnings (new ones prefixed by >>):
kernel/sysctl.c: In function 'do_proc_dointvec_minmax_conv':
>> kernel/sysctl.c:2558:14: warning: right shift count >= width of type [-Wshift-count-overflow]
*lvalp >> (sizeof(int) * 8))
^~
vim +2558 kernel/sysctl.c
2548
2549 static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
2550 int *valp,
2551 int write, void *data)
2552 {
2553 struct do_proc_dointvec_minmax_conv_param *param = data;
2554 if (write) {
2555 int val = *negp ? -*lvalp : *lvalp;
2556 if ((param->min && *param->min > val) ||
2557 (param->max && *param->max < val) ||
> 2558 *lvalp >> (sizeof(int) * 8))
2559 return -EINVAL;
2560 *valp = val;
2561 } else {
2562 int val = *valp;
2563 if (val < 0) {
2564 *negp = true;
2565 *lvalp = -(unsigned long)val;
2566 } else {
2567 *negp = false;
2568 *lvalp = (unsigned long)val;
2569 }
2570 }
2571 return 0;
2572 }
2573
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
[-- Attachment #2: .config.gz --]
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] sysctl: do not allow a 64bit value write in a 32bit knob
2018-08-27 20:27 [PATCH] sysctl: do not allow a 64bit value write in a 32bit knob Aristeu Rozanski
2018-08-28 4:43 ` kbuild test robot
@ 2018-08-28 7:21 ` kbuild test robot
1 sibling, 0 replies; 3+ messages in thread
From: kbuild test robot @ 2018-08-28 7:21 UTC (permalink / raw)
To: Aristeu Rozanski; +Cc: kbuild-all, linux-kernel, Luis R. Rodriguez, Kees Cook
[-- Attachment #1: Type: text/plain, Size: 4436 bytes --]
Hi Aristeu,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on v4.19-rc1 next-20180827]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Aristeu-Rozanski/sysctl-do-not-allow-a-64bit-value-write-in-a-32bit-knob/20180828-043801
config: i386-randconfig-x017-201834 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All warnings (new ones prefixed by >>):
In file included from include/linux/export.h:45:0,
from include/linux/linkage.h:7,
from include/linux/kernel.h:7,
from include/linux/list.h:9,
from include/linux/module.h:9,
from kernel/sysctl.c:21:
kernel/sysctl.c: In function 'do_proc_dointvec_minmax_conv':
kernel/sysctl.c:2558:14: warning: right shift count >= width of type [-Wshift-count-overflow]
*lvalp >> (sizeof(int) * 8))
^
include/linux/compiler.h:58:30: note: in definition of macro '__trace_if'
if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
^~~~
>> kernel/sysctl.c:2556:3: note: in expansion of macro 'if'
if ((param->min && *param->min > val) ||
^~
kernel/sysctl.c:2558:14: warning: right shift count >= width of type [-Wshift-count-overflow]
*lvalp >> (sizeof(int) * 8))
^
include/linux/compiler.h:58:42: note: in definition of macro '__trace_if'
if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
^~~~
>> kernel/sysctl.c:2556:3: note: in expansion of macro 'if'
if ((param->min && *param->min > val) ||
^~
kernel/sysctl.c:2558:14: warning: right shift count >= width of type [-Wshift-count-overflow]
*lvalp >> (sizeof(int) * 8))
^
include/linux/compiler.h:69:16: note: in definition of macro '__trace_if'
______r = !!(cond); \
^~~~
>> kernel/sysctl.c:2556:3: note: in expansion of macro 'if'
if ((param->min && *param->min > val) ||
^~
vim +/if +2556 kernel/sysctl.c
^1da177e Linus Torvalds 2005-04-16 2548
00b7c339 Amerigo Wang 2010-05-05 2549 static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
^1da177e Linus Torvalds 2005-04-16 2550 int *valp,
^1da177e Linus Torvalds 2005-04-16 2551 int write, void *data)
^1da177e Linus Torvalds 2005-04-16 2552 {
^1da177e Linus Torvalds 2005-04-16 2553 struct do_proc_dointvec_minmax_conv_param *param = data;
^1da177e Linus Torvalds 2005-04-16 2554 if (write) {
^1da177e Linus Torvalds 2005-04-16 2555 int val = *negp ? -*lvalp : *lvalp;
^1da177e Linus Torvalds 2005-04-16 @2556 if ((param->min && *param->min > val) ||
b79ce51f Aristeu Rozanski 2018-08-27 2557 (param->max && *param->max < val) ||
b79ce51f Aristeu Rozanski 2018-08-27 2558 *lvalp >> (sizeof(int) * 8))
^1da177e Linus Torvalds 2005-04-16 2559 return -EINVAL;
^1da177e Linus Torvalds 2005-04-16 2560 *valp = val;
^1da177e Linus Torvalds 2005-04-16 2561 } else {
^1da177e Linus Torvalds 2005-04-16 2562 int val = *valp;
^1da177e Linus Torvalds 2005-04-16 2563 if (val < 0) {
00b7c339 Amerigo Wang 2010-05-05 2564 *negp = true;
9a5bc726 Ilya Dryomov 2015-09-09 2565 *lvalp = -(unsigned long)val;
^1da177e Linus Torvalds 2005-04-16 2566 } else {
00b7c339 Amerigo Wang 2010-05-05 2567 *negp = false;
^1da177e Linus Torvalds 2005-04-16 2568 *lvalp = (unsigned long)val;
^1da177e Linus Torvalds 2005-04-16 2569 }
^1da177e Linus Torvalds 2005-04-16 2570 }
^1da177e Linus Torvalds 2005-04-16 2571 return 0;
^1da177e Linus Torvalds 2005-04-16 2572 }
^1da177e Linus Torvalds 2005-04-16 2573
:::::: The code at line 2556 was first introduced by commit
:::::: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Linux-2.6.12-rc2
:::::: TO: Linus Torvalds <torvalds@ppc970.osdl.org>
:::::: CC: Linus Torvalds <torvalds@ppc970.osdl.org>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
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2018-08-27 20:27 [PATCH] sysctl: do not allow a 64bit value write in a 32bit knob Aristeu Rozanski
2018-08-28 4:43 ` kbuild test robot
2018-08-28 7:21 ` kbuild test robot
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