linux-kernel - Re: [PATCH v2 1/2] checkpatch: add uninitialized pointer with _

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Message-ID: <66575ceb29493f3b9c5b8bb94f4f66bf21d53211.camel@gmail.com>
Date: Sat, 25 Oct 2025 09:07:56 +0530
From: ally heev <allyheev@...il.com>
To: Joe Perches <joe@...ches.com>, Dwaipayan Ray <dwaipayanray1@...il.com>, 
 Lukas Bulwahn <lukas.bulwahn@...il.com>, Jonathan Corbet <corbet@....net>,
 Andy Whitcroft <apw@...onical.com>
Cc: workflows@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Dan Carpenter <dan.carpenter@...aro.org>,
 David Hunter <david.hunter.linux@...il.com>, Shuah Khan
 <skhan@...uxfoundation.org>, Viresh Kumar	 <vireshk@...nel.org>, Nishanth
 Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,  linux-pm
 <linux-pm@...r.kernel.org>, dan.j.williams@...el.com
Subject: Re: [PATCH v2 1/2] checkpatch: add uninitialized pointer with
 __free attribute check

On Fri, 2025-10-24 at 11:14 -0700, Joe Perches wrote:
> On Fri, 2025-10-24 at 22:59 +0530, Ally Heev wrote:
> > uninitialized pointers with __free attribute can cause undefined
> > behaviour as the memory allocated to the pointer is freed
> > automatically when the pointer goes out of scope.
> > add check in checkpatch to detect such issues
> > 
> > Suggested-by: Dan Carpenter <dan.carpenter@...aro.org>
> > Link: https://lore.kernel.org/all/8a4c0b43-cf63-400d-b33d-d9c447b7e0b9@suswa.mountain/
> > Acked-by: Dan Williams <dan.j.williams@...el.com>
> > Signed-off-by: Ally Heev <allyheev@...il.com>
> > ---
> >  Documentation/dev-tools/checkpatch.rst | 5 +++++
> >  scripts/checkpatch.pl                  | 7 +++++++
> >  2 files changed, 12 insertions(+)
> > 
> > diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
> > index d5c47e560324fb2399a5b1bc99c891ed1de10535..1a304bf38bcd27e50bbb7cd4383b07ac54d20b0a 100644
> > --- a/Documentation/dev-tools/checkpatch.rst
> > +++ b/Documentation/dev-tools/checkpatch.rst
> > @@ -1009,6 +1009,11 @@ Functions and Variables
> >  
> >        return bar;
> >  
> > +  **UNINITIALIZED_PTR_WITH_FREE**
> > +    Pointers with __free attribute should be initialized. Not doing so
> > +    may lead to undefined behavior as the memory allocated (garbage,
> > +    in case not initialized) to the pointer is freed automatically
> > +    when the pointer goes out of scope.
> >  
> >  Permissions
> >  -----------
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 92669904eecc7a8d2afd3f2625528e02b6d17cd6..1009a4a065e910143dabeee6640b3b3a4bd3fe06 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -509,6 +509,7 @@ our $InitAttributeData = qr{$InitAttributePrefix(?:initdata\b)};
> >  our $InitAttributeConst = qr{$InitAttributePrefix(?:initconst\b)};
> >  our $InitAttributeInit = qr{$InitAttributePrefix(?:init\b)};
> >  our $InitAttribute = qr{$InitAttributeData|$InitAttributeConst|$InitAttributeInit};
> > +our $FreeAttribute = qr{__free\s*\(\s*$Ident\s*\)};
> 
> If you are really suggesting using this, and I don't think it's
> particularly useful, please use
> 
> out $InitAttributeFree = qr{$InitAttributePrefix(?:free\s*\(\s*$Ident\s*\)};

Thanks, I'll check it out

> >  
> >  # Notes to $Attribute:
> >  # We need \b after 'init' otherwise 'initconst' will cause a false positive in a check
> > @@ -7721,6 +7722,12 @@ sub process {
> >  				ERROR("MISSING_SENTINEL", "missing sentinel in ID array\n" . "$here\n$stat\n");
> >  			}
> >  		}
> > +
> > +# check for uninitialized pointers with __free attribute
> > +		while ($line =~ /\*\s*($Ident)\s+$FreeAttribute\s*[,;]/g) {
> > +			ERROR("UNINITIALIZED_PTR_WITH_FREE",
> > +			      "pointer '$1' with __free attribute should be initialized\n" . $herecurr);
> > +		}
> >  	}
> >  
> >  	# If we have no input at all, then there is nothing to report on