linux-kernel - Re: [PATCH] kconfig: check for a NULL pointer before access

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: <2f6201d1-4e18-43ab-aadd-27643d57dab6@infradead.org>
Date: Thu, 22 May 2025 17:16:29 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Bill Wendling <morbo@...gle.com>, Masahiro Yamada <masahiroy@...nel.org>,
 Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kconfig: check for a NULL pointer before access

Hi,

On 5/22/25 5:07 PM, Bill Wendling wrote:
> The call to 'prop_get_symbol' may return NULL in some cases. The if-then
> statement accesses the returned value without checking if it's
> non-NULL. After inlining, the compiler may treat the conditional as
> 'undefined behavior', which the compiler may take the opportunity to do
> whatever it wants with the UB path. This patch simply adds a check to
> ensure that 'def_sym' is non-NULL to avoid this behavior.
> 
> Signed-off-by: Bill Wendling <morbo@...gle.com>
> ---
> Cc: Masahiro Yamada <masahiroy@...nel.org>
> Cc: linux-kbuild@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> ---
>  scripts/kconfig/symbol.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
> index d57f8cbba291..9c5068225328 100644
> --- a/scripts/kconfig/symbol.c
> +++ b/scripts/kconfig/symbol.c
> @@ -272,7 +272,7 @@ struct symbol *sym_choice_default(struct menu *choice)
>   if (prop->visible.tri == no)
>   continue;
>   def_sym = prop_get_symbol(prop);
> - if (def_sym->visible != no)
> + if (def_sym && def_sym->visible != no)
>   return def_sym;
>   }
> 

The patch is missing the source file's indentation.
(spaces/tabs are lost)

-- 
~Randy