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Groups > linux.kernel > #1533200 > unrolled thread
| Started by | Yisheng Xie <xieyisheng1@huawei.com> |
|---|---|
| First post | 2016-11-30 11:40 +0100 |
| Last post | 2016-12-06 14:00 +0100 |
| Articles | 6 — 4 participants |
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[PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl Yisheng Xie <xieyisheng1@huawei.com> - 2016-11-30 11:40 +0100
Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl Andrew Morton <akpm@linux-foundation.org> - 2016-11-30 22:40 +0100
Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl Yisheng Xie <xieyisheng1@huawei.com> - 2016-12-02 08:00 +0100
Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl ebiederm@xmission.com (Eric W. Biederman) - 2016-12-02 20:30 +0100
Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl Xishi Qiu <qiuxishi@huawei.com> - 2016-12-05 07:20 +0100
Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl Yisheng Xie <xieyisheng1@huawei.com> - 2016-12-06 14:00 +0100
| From | Yisheng Xie <xieyisheng1@huawei.com> |
|---|---|
| Date | 2016-11-30 11:40 +0100 |
| Subject | [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl |
| Message-ID | <sJasW-4VL-9@gated-at.bofh.it> |
I tried to echo an invalid value to an unsigned long type sysctl on
4.9.0-rc6:
linux:~# cat /proc/sys/vm/user_reserve_kbytes
131072
linux:~# echo -1 > /proc/sys/vm/user_reserve_kbytes
linux:~# cat /proc/sys/vm/user_reserve_kbytes
131072
The echo operation got error and the value do not write to
user_reserve_kbytes, however, user do not know it until checking
the value again.
This patch return -EINVAL when write an invalid value to unsigned
long type sysctl to make user know what happened without
checking its value once more, just as what proc_douintvec do.
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
---
This is a patchset after RFC, you can see the former discussion at
https://lkml.org/lkml/2016/11/26/48
Any comment is more than welcome.
Thanks,
Yisheng Xie.
---
kernel/sysctl.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 706309f..40e9285 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2485,10 +2485,14 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
sizeof(proc_wspace_sep), NULL);
if (err)
break;
- if (neg)
- continue;
- if ((min && val < *min) || (max && val > *max))
- continue;
+ if (neg) {
+ err = -EINVAL;
+ break;
+ }
+ if ((min && val < *min) || (max && val > *max)) {
+ err = -EINVAL;
+ break;
+ }
*i = val;
} else {
val = convdiv * (*i) / convmul;
--
1.7.12.4
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| From | Andrew Morton <akpm@linux-foundation.org> |
|---|---|
| Date | 2016-11-30 22:40 +0100 |
| Subject | Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl |
| Message-ID | <sJkLD-2XW-7@gated-at.bofh.it> |
| In reply to | #1533200 |
On Wed, 30 Nov 2016 18:30:52 +0800 Yisheng Xie <xieyisheng1@huawei.com> wrote: > I tried to echo an invalid value to an unsigned long type sysctl on > 4.9.0-rc6: > linux:~# cat /proc/sys/vm/user_reserve_kbytes > 131072 > linux:~# echo -1 > /proc/sys/vm/user_reserve_kbytes > linux:~# cat /proc/sys/vm/user_reserve_kbytes > 131072 > > The echo operation got error and the value do not write to > user_reserve_kbytes, however, user do not know it until checking > the value again. > > This patch return -EINVAL when write an invalid value to unsigned > long type sysctl to make user know what happened without > checking its value once more, just as what proc_douintvec do. hmpf. # echo 18446744073709551615 > /proc/sys/vm/user_reserve_kbytes # cat /proc/sys/vm/user_reserve_kbytes 18446744073709551615 I think that when taking in an unsigned long the kernel should simply treat -1 as 0xffffffff (or 0xffffffffffffffff). It's natural and normal and everyone knows what it means?
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| From | Yisheng Xie <xieyisheng1@huawei.com> |
|---|---|
| Date | 2016-12-02 08:00 +0100 |
| Subject | Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl |
| Message-ID | <sJPZ7-5Y-1@gated-at.bofh.it> |
| In reply to | #1533590 |
On 2016/12/1 5:33, Andrew Morton wrote: > On Wed, 30 Nov 2016 18:30:52 +0800 Yisheng Xie <xieyisheng1@huawei.com> wrote: > >> I tried to echo an invalid value to an unsigned long type sysctl on >> 4.9.0-rc6: >> linux:~# cat /proc/sys/vm/user_reserve_kbytes >> 131072 >> linux:~# echo -1 > /proc/sys/vm/user_reserve_kbytes >> linux:~# cat /proc/sys/vm/user_reserve_kbytes >> 131072 >> >> The echo operation got error and the value do not write to >> user_reserve_kbytes, however, user do not know it until checking >> the value again. >> >> This patch return -EINVAL when write an invalid value to unsigned >> long type sysctl to make user know what happened without >> checking its value once more, just as what proc_douintvec do. > > hmpf. > > # echo 18446744073709551615 > /proc/sys/vm/user_reserve_kbytes > # cat /proc/sys/vm/user_reserve_kbytes > 18446744073709551615 > > I think that when taking in an unsigned long the kernel should simply > treat -1 as 0xffffffff (or 0xffffffffffffffff). It's natural and > normal and everyone knows what it means? > Hi Andrew, Thank you for your reply. Do you means it should be like this: # echo -1 > /proc/sys/vm/user_reserve_kbytes # cat /proc/sys/vm/user_reserve_kbytes 18446744073709551615 I looks ok to me, however, I not sure whether other code in the kernel will also use its complement if user write a negative number for an unsigned long. Does anyone have other opinion ? Thanks Yisheng Xie. > > > > . >
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| From | ebiederm@xmission.com (Eric W. Biederman) |
|---|---|
| Date | 2016-12-02 20:30 +0100 |
| Message-ID | <sK1GV-7VR-1@gated-at.bofh.it> |
| In reply to | #1534697 |
Yisheng Xie <xieyisheng1@huawei.com> writes: > On 2016/12/1 5:33, Andrew Morton wrote: >> On Wed, 30 Nov 2016 18:30:52 +0800 Yisheng Xie <xieyisheng1@huawei.com> wrote: >> >>> I tried to echo an invalid value to an unsigned long type sysctl on >>> 4.9.0-rc6: >>> linux:~# cat /proc/sys/vm/user_reserve_kbytes >>> 131072 >>> linux:~# echo -1 > /proc/sys/vm/user_reserve_kbytes >>> linux:~# cat /proc/sys/vm/user_reserve_kbytes >>> 131072 >>> >>> The echo operation got error and the value do not write to >>> user_reserve_kbytes, however, user do not know it until checking >>> the value again. >>> >>> This patch return -EINVAL when write an invalid value to unsigned >>> long type sysctl to make user know what happened without >>> checking its value once more, just as what proc_douintvec do. >> >> hmpf. >> >> # echo 18446744073709551615 > /proc/sys/vm/user_reserve_kbytes >> # cat /proc/sys/vm/user_reserve_kbytes >> 18446744073709551615 >> >> I think that when taking in an unsigned long the kernel should simply >> treat -1 as 0xffffffff (or 0xffffffffffffffff). It's natural and >> normal and everyone knows what it means? >> > Hi Andrew, > Thank you for your reply. > Do you means it should be like this: > # echo -1 > /proc/sys/vm/user_reserve_kbytes > # cat /proc/sys/vm/user_reserve_kbytes > 18446744073709551615 > > I looks ok to me, however, I not sure whether other code in the kernel > will also use its complement if user write a negative number for an > unsigned long. Does anyone have other opinion ? Largely we need to be very careful with changing these functions as they have been around for a long time, and have a very diverse set of users. So while changes are possible a reasonable argument needs to be made that nothing in userspace cares. Eric
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| From | Xishi Qiu <qiuxishi@huawei.com> |
|---|---|
| Date | 2016-12-05 07:20 +0100 |
| Subject | Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl |
| Message-ID | <sKUN3-OF-5@gated-at.bofh.it> |
| In reply to | #1535139 |
On 2016/12/3 3:24, Eric W. Biederman wrote: > Yisheng Xie <xieyisheng1@huawei.com> writes: > >> On 2016/12/1 5:33, Andrew Morton wrote: >>> On Wed, 30 Nov 2016 18:30:52 +0800 Yisheng Xie <xieyisheng1@huawei.com> wrote: >>> >>>> I tried to echo an invalid value to an unsigned long type sysctl on >>>> 4.9.0-rc6: >>>> linux:~# cat /proc/sys/vm/user_reserve_kbytes >>>> 131072 >>>> linux:~# echo -1 > /proc/sys/vm/user_reserve_kbytes >>>> linux:~# cat /proc/sys/vm/user_reserve_kbytes >>>> 131072 >>>> >>>> The echo operation got error and the value do not write to >>>> user_reserve_kbytes, however, user do not know it until checking >>>> the value again. >>>> >>>> This patch return -EINVAL when write an invalid value to unsigned >>>> long type sysctl to make user know what happened without >>>> checking its value once more, just as what proc_douintvec do. >>> >>> hmpf. >>> >>> # echo 18446744073709551615 > /proc/sys/vm/user_reserve_kbytes >>> # cat /proc/sys/vm/user_reserve_kbytes >>> 18446744073709551615 >>> >>> I think that when taking in an unsigned long the kernel should simply >>> treat -1 as 0xffffffff (or 0xffffffffffffffff). It's natural and >>> normal and everyone knows what it means? >>> >> Hi Andrew, >> Thank you for your reply. >> Do you means it should be like this: >> # echo -1 > /proc/sys/vm/user_reserve_kbytes >> # cat /proc/sys/vm/user_reserve_kbytes >> 18446744073709551615 >> >> I looks ok to me, however, I not sure whether other code in the kernel >> will also use its complement if user write a negative number for an >> unsigned long. Does anyone have other opinion ? > > Largely we need to be very careful with changing these functions as > they have been around for a long time, and have a very diverse set of > users. > > So while changes are possible a reasonable argument needs to be made > that nothing in userspace cares. > > Eric > Hi Eric, This patch is aimed to change the return value if write invalid value to ulong type sysctl, just to keep the same as int type sysctl. Thanks, Xishi Qiu > . >
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| From | Yisheng Xie <xieyisheng1@huawei.com> |
|---|---|
| Date | 2016-12-06 14:00 +0100 |
| Subject | Re: [PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl |
| Message-ID | <sLnvI-29V-25@gated-at.bofh.it> |
| In reply to | #1535139 |
On 2016/12/3 3:24, Eric W. Biederman wrote: > Yisheng Xie <xieyisheng1@huawei.com> writes: > >> On 2016/12/1 5:33, Andrew Morton wrote: >>> On Wed, 30 Nov 2016 18:30:52 +0800 Yisheng Xie <xieyisheng1@huawei.com> wrote: >>> >>>> I tried to echo an invalid value to an unsigned long type sysctl on >>>> 4.9.0-rc6: >>>> linux:~# cat /proc/sys/vm/user_reserve_kbytes >>>> 131072 >>>> linux:~# echo -1 > /proc/sys/vm/user_reserve_kbytes >>>> linux:~# cat /proc/sys/vm/user_reserve_kbytes >>>> 131072 >>>> >>>> The echo operation got error and the value do not write to >>>> user_reserve_kbytes, however, user do not know it until checking >>>> the value again. >>>> >>>> This patch return -EINVAL when write an invalid value to unsigned >>>> long type sysctl to make user know what happened without >>>> checking its value once more, just as what proc_douintvec do. >>> >>> hmpf. >>> >>> # echo 18446744073709551615 > /proc/sys/vm/user_reserve_kbytes >>> # cat /proc/sys/vm/user_reserve_kbytes >>> 18446744073709551615 >>> >>> I think that when taking in an unsigned long the kernel should simply >>> treat -1 as 0xffffffff (or 0xffffffffffffffff). It's natural and >>> normal and everyone knows what it means? >>> >> Hi Andrew, >> Thank you for your reply. >> Do you means it should be like this: >> # echo -1 > /proc/sys/vm/user_reserve_kbytes >> # cat /proc/sys/vm/user_reserve_kbytes >> 18446744073709551615 >> >> I looks ok to me, however, I not sure whether other code in the kernel >> will also use its complement if user write a negative number for an >> unsigned long. Does anyone have other opinion ? > > Largely we need to be very careful with changing these functions as > they have been around for a long time, and have a very diverse set of > users. Hi Eric, Thanks for your reply. That right. > > So while changes are possible a reasonable argument needs to be made > that nothing in userspace cares. > So the patch's original aim that return -EINVAL when user write invalid val to ulong type sysctl is more reasonable, Right? Thanks, Yisheng Xie > Eric > > . >
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