Re: printk()s of user-supplied strings

[Krzysztof Halasa <khc@pm.waw.pl>]

Willy Tarreau <w@1wt.eu> writes:

> Well, I'm not sure about this. Nearly all patches which get merged pass
> through a public review first, and when you see how many replies you get
> for and 'else' and and 'if' on two different lines, I expect lots of
> spontaneous replies such as "use %S for user-supplied strings".

I wouldn't rely on that.

>> A solution would be to normally use "%S" and only use
>> "%s" where "%S" wouldn't work.  In that case, we could as well swap "%s"
>> and "%S", though - hardening the existing "%s" and introducing "%S" for
>> those callers that depend on the old behavior.

I think it's the way to go.

> I'd rather not change "%s" semantics if we introduce another specifier
> which does exactly what we would expect "%s" to do.

Both would be equivalent in most cases. It's better to use "%s" for
most cases (either secured or not) and leave "%S" for the bunch of
special cases whose authors better know what are they doing.

> I will try your proposal to retain the trailing '\n' unescaped.

I think with "%s" and "%S" this is no longer needed.
-- 
Krzysztof Halasa