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*\(\s*$Ident\s*\)};
>
> # 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
