Re: [PATCH] kernel/sysctl.c: If "count" including the terminating byte '\0' the write system call should retrun success.

[Eric W. Biederman]

On September 15, 2015 4:30:56 AM CDT, Sean Fu <fxinrong@xxxxxxxxx> wrote:
>On Mon, Sep 14, 2015 at 12:44 AM, Eric W. Biederman
><ebiederm@xxxxxxxxxxxx> wrote:
>> Sean Fu <fxinrong@xxxxxxxxx> writes:
>>
>>> On Sat, Sep 12, 2015 at 1:01 AM, Eric W. Biederman
>>> <ebiederm@xxxxxxxxxxxx> wrote:
>>>> Sean Fu <fxinrong@xxxxxxxxx> writes:
>> '\0' is not and has never been valid in a text file.
>> proc files are a text interface.
>> Expecting '\0' to be accepted is very strange, and apparently there
>is
>> only one program in existence that does.
>>
>> That a trailing '\0' was ever accepted was due to a bug in the code.
>>
>> Accepting '\0' in general in a text interface is a very dangerous and
>> buggy pattern so it must be done very carefully or else other
>> regressions or bugs could be easily introduced.
>Ok,
>Could you please give me more detail about the potential risk from the
>patch?

Regressions.  AKA There may now be programs that depend on writing a  '\0' failing.

>What is the different behavior between the patch and old kernel?
>It seems like entirely same.

Not at all.  And clear explanations have already been given.

Eric

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/