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 <[email protected]>
> > Link:
> > https://lore.kernel.org/all/[email protected]/
> > Acked-by: Dan Williams <[email protected]>
> > Signed-off-by: Ally Heev <[email protected]>
> > ---
> > 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
