linux-kernel - Re: [PATCH 08/10] checkpatch: Remove awareness of uninitialized

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Date:   Wed, 3 Jun 2020 18:40:09 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Joe Perches <joe@...ches.com>
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andy Whitcroft <apw@...onical.com>, x86@...nel.org,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        b43-dev@...ts.infradead.org, netdev@...r.kernel.org,
        linux-wireless@...r.kernel.org, linux-ide@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-mm@...ck.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH 08/10] checkpatch: Remove awareness of
 uninitialized_var() macro

On Wed, Jun 03, 2020 at 05:02:29PM -0700, Joe Perches wrote:
> On Wed, 2020-06-03 at 16:32 -0700, Kees Cook wrote:
> > Using uninitialized_var() is dangerous as it papers over real bugs[1]
> > (or can in the future), and suppresses unrelated compiler warnings
> > (e.g. "unused variable"). If the compiler thinks it is uninitialized,
> > either simply initialize the variable or make compiler changes.
> > 
> > In preparation for removing[2] the[3] macro[4], effectively revert
> > commit 16b7f3c89907 ("checkpatch: avoid warning about uninitialized_var()")
> > and remove all remaining mentions of uninitialized_var().
> > 
> > [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> > [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> > [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> > [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
> 
> nack.  see below.
> 
> I'd prefer a simple revert, but it shouldn't
> be done here.

What do you mean? (I can't understand this and "fine by me" below?)

> 
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > @@ -4075,7 +4074,7 @@ sub process {
> >  		}
> >  
> >  # check for function declarations without arguments like "int foo()"
> > -		if ($line =~ /(\b$Type\s*$Ident)\s*\(\s*\)/) {
> > +		if ($line =~ /(\b$Type\s+$Ident)\s*\(\s*\)/) {
> 
> This isn't right because $Type includes a possible trailing *
> where there isn't a space between $Type and $Ident

Ah, hm, that was changed in the mentioned commit:

-               if ($line =~ /(\b$Type\s+$Ident)\s*\(\s*\)/) {
+               if ($line =~ /(\b$Type\s*$Ident)\s*\(\s*\)/) {

> 
> e.g.:	int *bar(void);
> 
> Other than that, fine by me...

Thanks for looking it over! I'll adjust it however you'd like. :)

-- 
Kees Cook