Re: [PATCH] sysctl: terminate strings also on \r

[Kees Cook]

On Wed, Oct 22, 2014 at 4:26 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 21 Oct 2014 13:21:37 -0700 Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
>> From: Paul Wise <pabs3@xxxxxxxxxxxxx>
>>
>> This partially mitigates a common strategy used by attackers for hiding
>> the full contents of strings in procfs from naive sysadmins who use cat,
>> more or sysctl to inspect the contents of strings in procfs.
>>
>> ...
>>
>> --- a/kernel/sysctl.c
>> +++ b/kernel/sysctl.c
>> @@ -1739,7 +1739,7 @@ static int _proc_do_string(char *data, int maxlen, int write,
>>               while ((p - buffer) < *lenp && len < maxlen - 1) {
>>                       if (get_user(c, p++))
>>                               return -EFAULT;
>> -                     if (c == 0 || c == '\n')
>> +                     if (c == 0 || c == '\n' || c == '\r')
>>                               break;
>>                       data[len++] = c;
>>               }
>
> There are no valid uses of \r in a procfs write?

I struggle to imagine one; everything I found that uses proc_dostring
seems to be names, paths, and commands.

-Kees

-- 
Kees Cook
Chrome OS Security
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