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SubjectRe: [PATCH v3] proc_sysctl: fix oops caused by incorrect command parameters.
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On 2021/1/12 12:33, Andrew Morton wrote:
> On Tue, 12 Jan 2021 11:31:55 +0800 Xiaoming Ni <nixiaoming@huawei.com> wrote:
>
>> The process_sysctl_arg() does not check whether val is empty before
>> invoking strlen(val). If the command line parameter () is incorrectly
>> configured and val is empty, oops is triggered.
>>
>> --- a/fs/proc/proc_sysctl.c
>> +++ b/fs/proc/proc_sysctl.c
>> @@ -1770,6 +1770,9 @@ static int process_sysctl_arg(char *param, char *val,
>> return 0;
>> }
>>
>> + if (!val)
>> + return -EINVAL;
>> +
>
> I think v2 (return 0) was preferable. Because all the other error-out
> cases in process_sysctl_arg() also do a `return 0'.

https://lore.kernel.org/lkml/bc098af4-c0cd-212e-d09d-46d617d0acab@huawei.com/

patch4:
+++ b/fs/proc/proc_sysctl.c
@@ -1757,6 +1757,9 @@ static int process_sysctl_arg(char *param,
char *val,
loff_t pos = 0;
ssize_t wret;

+ if (!val)
+ return 0;
+
if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
param += sizeof("sysctl") - 1;

Is this the version you're talking about?

>
> If we're going to do a separate "patch: make process_sysctl_arg()
> return an errno instead of 0" then fine, we can discuss that. But it's
> conceptually a different work from fixing this situation.
> .
>
However, are the logs generated by process_sysctl_arg() clearer and more
accurate than parse_args()? Should the logs generated by
process_sysctl_arg() be deleted?

Thanks
Xiaoming Ni

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