linux-kernel - Re: [PATCH] checkpatch: add uninitialized pointer with _

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <68f7c9585ca25_10e210039@dwillia2-mobl4.notmuch>
Date: Tue, 21 Oct 2025 10:56:40 -0700
From: <dan.j.williams@...el.com>
To: Joe Perches <joe@...ches.com>, Ally Heev <allyheev@...il.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>
Subject: Re: [PATCH] checkpatch: add uninitialized pointer with __free
 attribute check

Joe Perches wrote:
[..]
> drivers/opp/core.c-unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
> drivers/opp/core.c-{
> drivers/opp/core.c:     struct opp_table *opp_table __free(put_opp_table);
> drivers/opp/core.c-
> drivers/opp/core.c-     opp_table = _find_opp_table(dev);

The documentation in include/linux/cleanup.h recommends always combining
declaration and allocation. The rule of "variable declarations at the
top of the function" is relaxed for scope-based cleanup.

> An aside found while using grep:
> 
> There are uses of DEFINE_FREE that seem to have an unnecessary trailing ;
> 
> $ git grep -w DEFINE_FREE | grep ';'
> drivers/firmware/efi/libstub/efistub.h:DEFINE_FREE(efi_pool, void *, if (_T) efi_bs_call(free_pool, _T));
> drivers/fwctl/mlx5/main.c:DEFINE_FREE(mlx5ctl, struct mlx5ctl_dev *, if (_T) fwctl_put(&_T->fwctl));
> drivers/pci/msi/msi.c:DEFINE_FREE(free_msi_irqs, struct pci_dev *, if (_T) pci_free_msi_irqs(_T));
> drivers/tty/vt/vc_screen.c:DEFINE_FREE(free_page_ptr, void *, if (_T) free_page((unsigned long)_T));
> fs/pstore/inode.c:DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T));
> include/linux/cpumask.h:DEFINE_FREE(free_cpumask_var, struct cpumask *, if (_T) free_cpumask_var(_T));
> include/linux/execmem.h:DEFINE_FREE(execmem, void *, if (_T) execmem_free(_T));
> include/linux/fwctl.h:DEFINE_FREE(fwctl, struct fwctl_device *, if (_T) fwctl_put(_T));
> net/core/dev.h:DEFINE_FREE(netdev_unlock, struct net_device *, if (_T) netdev_unlock(_T));

Note that until this issue is addressed:

https://github.com/universal-ctags/ctags/issues/4289

...it may be the case that Linux *wants* to allow dangling semicolon
for DEFINE_FREE() if only to help "make tags" find the symbols following
DEFINE_FREE() invocations.

It is interesting that this happens to not impact DEFINE_FREE()
instances that use IS_ERR_OR_NULL.