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Subject[PATCH] kernel/sysctl: return -EINVAL if write invalid val to ulong type sysctl
Date
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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