linux-kernel - Re: [PATCH v2] kconfig: Avoid prompting for transitional symbols

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Message-ID: <B1170B95-F9B4-43F5-90A7-B31076CDA3F3@kernel.org>
Date: Tue, 30 Sep 2025 23:00:07 -0700
From: Kees Cook <kees@...nel.org>
To: Andrew Donnellan <ajd@...ux.ibm.com>,
 Vegard Nossum <vegard.nossum@...cle.com>
CC: Linus Torvalds <torvalds@...ux-foundation.org>,
 Masahiro Yamada <masahiroy@...nel.org>,
 Nathan Chancellor <nathan@...nel.org>, Petr Vorel <pvorel@...e.cz>,
 linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] kconfig: Avoid prompting for transitional symbols



On September 30, 2025 9:21:07 PM PDT, Andrew Donnellan <ajd@...ux.ibm.com> wrote:
>On Tue, 2025-09-30 at 08:45 -0700, Kees Cook wrote:
>> The "transitional" symbol keyword, while working with the "olddefconfig"
>> target, was prompting during "oldconfig". This occurred because these
>> symbols were not being marked as user-defined when they received values
>> from transitional symbols that had user values. The "olddefconfig" target
>> explicitly doesn't prompt for anything, so this deficiency wasn't noticed.
>> 
>> The issue manifested when a symbol's value came from a transitional
>> symbol's user value but the receiving symbol wasn't marked with
>> SYMBOL_DEF_USER. Thus the "oldconfig" logic would then prompt for these
>> symbols unnecessarily.
>> 
>> Check after value calculation whether a symbol without a user value
>> gets its value from a single transitional symbol that does have a user
>> value. In such cases, mark the receiving symbol as user-defined to
>> prevent prompting.
>> 
>> Update regression tests to verify that symbols with transitional defaults
>> are not prompted in "oldconfig", except when conditional defaults evaluate
>> to 'no' and should legitimately be prompted.
>> 
>> Build tested with "make testconfig".
>> 
>> Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
>> Closes:
>> https://lore.kernel.org/lkml/CAHk-=wgZjUk4Cy2XgNkTrQoO8XCmNUHrTe5D519Fij1POK+3qw@mail.gmail.com/
>> Fixes: 05020835c86e ("kconfig: Add transitional symbol attribute for migration
>> support")
>
>I think this should be f9afce4f32e9.

Indeed. I fixed this before I pushed it to -next; thank you!

-Kees


-- 
Kees Cook