Commit 0902b3cb authored by Kees Cook's avatar Kees Cook
Browse files

kconfig: Avoid prompting for transitional symbols 



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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Closes: https://lore.kernel.org/lkml/CAHk-=wgZjUk4Cy2XgNkTrQoO8XCmNUHrTe5D519Fij1POK+3qw@mail.gmail.com/
Fixes: f9afce4f ("kconfig: Add transitional symbol attribute for migration support")
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Link: https://lore.kernel.org/r/20250930154514.it.623-kees@kernel.org


Signed-off-by: default avatarKees Cook <kees@kernel.org>
parent fd94619c

scripts/kconfig/symbol.c

+14 −1
Original line number Diff line number Diff line
@@ -411,7 +411,7 @@ bool sym_dep_errors(void) 
void sym_calc_value(struct symbol *sym)

{

	struct symbol_value newval, oldval;

	struct property *prop;

	struct property *prop = NULL;

	struct menu *choice_menu;



	if (!sym)
@@ -520,6 +520,19 @@ void sym_calc_value(struct symbol *sym) 
		;

	}



	/*

	 * If the symbol lacks a user value but its value comes from a

	 * single transitional symbol with an existing user value, mark

	 * this symbol as having a user value to avoid prompting.

	 */

	if (prop && !sym_has_value(sym)) {

		struct symbol *ds = prop_get_symbol(prop);

		if (ds && (ds->flags & SYMBOL_TRANS) && sym_has_value(ds)) {

			sym->def[S_DEF_USER] = newval;

			sym->flags |= SYMBOL_DEF_USER;

		}

	}



	sym->curr = newval;

	sym_validate_range(sym);

scripts/kconfig/tests/transitional/Kconfig

+32 −0
Original line number Diff line number Diff line
@@ -96,5 +96,37 @@ config OLD_WITH_HELP 
	help

	  This transitional symbol has a help section to validate that help is allowed.



# Test that we can set something to =n via transitional symbol

config NEW_DISABLED

	tristate "Check for setting to disabled"

	default OLD_DISABLED



config OLD_DISABLED

	tristate

	transitional



# Test that a potential new value disappears if it lacks a prompt

config NEW_DISABLED_UNSAVED

	tristate

	default OLD_DISABLED



config OLD_DISABLED_UNSAVED

	tristate

	transitional



# Test conditional default: transitional value should not prevent prompting

# when default visibility makes the expression evaluate to 'no'

config DEPENDENCY_TEST

	bool "Dependency for testing"

	default n



config NEW_CONDITIONAL_DEFAULT

	bool "New option with conditional default"

	default OLD_CONDITIONAL_DEFAULT if DEPENDENCY_TEST



config OLD_CONDITIONAL_DEFAULT

	bool

	transitional



config REGULAR_OPTION

	bool "Regular option"

scripts/kconfig/tests/transitional/__init__.py

+7 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ This tests that: 
- OLD_* options in existing .config cause NEW_* options to be set

- OLD_* options are not written to the new .config file

- NEW_* options appear in the new .config file with correct values

- NEW_* options with defaults from transitional symbols are not prompted

- All Kconfig types work correctly: bool, tristate, string, hex, int

- User-set NEW values take precedence over conflicting OLD transitional values

"""
@@ -16,3 +17,9 @@ def test(conf): 


    # Check that the configuration matches expected output

    assert conf.config_contains('expected_config')



    # Test oldconfig to ensure symbols with transitional defaults are not prompted

    assert conf.oldconfig(dot_config='initial_config', in_keys='n\n') == 0



    # Except for when conditional default evaluates to 'no'

    assert conf.stdout_contains('expected_stdout')

scripts/kconfig/tests/transitional/expected_config

+3 −0
Original line number Diff line number Diff line
@@ -9,4 +9,7 @@ CONFIG_NEW_STRING_PRECEDENCE="user value" 
CONFIG_NEW_TRISTATE_PRECEDENCE=y

CONFIG_NEW_HEX_PRECEDENCE=0xABCD

CONFIG_NEW_INT_PRECEDENCE=100

# CONFIG_NEW_DISABLED is not set

# CONFIG_DEPENDENCY_TEST is not set

# CONFIG_NEW_CONDITIONAL_DEFAULT is not set

# CONFIG_REGULAR_OPTION is not set

scripts/kconfig/tests/transitional/expected_stdout

0 → 100644
+1 −0
Original line number Diff line number Diff line 
New option with conditional default (NEW_CONDITIONAL_DEFAULT) [N/y/?] (NEW) n