[PATCH 4/4] kconfig: prevent out-of-bounds user input for numeric options

Currently, user input of out-of-bounds values for 'int' and 'hex' options
is possible, leading to later silent failures in Kconfig if that value is
used in a comparison, or a warning by GCC or error by Clang if used in the
C code.

Let's factor out the out-of-bounds check on constants, so that it can be
reused for checking user input.

The frontend will now reject an attempted user input of an out-of-bounds
numeric value, similarly to how a value outside the active 'range' already
does.

For migration of existing configurations, a .config file with an
out-of-bounds numeric value will be allowed for now, but will warn the
user when read in by confdata.c

Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Julian Braha <[email protected]>
---
 scripts/kconfig/confdata.c                    |  6 +++++
 scripts/kconfig/lkc_proto.h                   |  1 +
 scripts/kconfig/menu.c                        | 11 +++-----
 scripts/kconfig/symbol.c                      | 20 +++++++++++++++
 scripts/kconfig/tests/warn_num_bounds/Kconfig | 24 ++++++++++++++++++
 .../kconfig/tests/warn_num_bounds/__init__.py | 25 +++++++++++++++++++
 scripts/kconfig/tests/warn_num_bounds/config  |  7 ++++++
 .../tests/warn_num_bounds/expected_config     | 11 ++++++++
 .../warn_num_bounds/expected_config_stderr    |  3 +++
 .../warn_num_bounds/expected_frontend_config  | 11 ++++++++
 .../warn_num_bounds/expected_frontend_stderr  |  0
 11 files changed, 111 insertions(+), 8 deletions(-)
 create mode 100644 scripts/kconfig/tests/warn_num_bounds/Kconfig
 create mode 100644 scripts/kconfig/tests/warn_num_bounds/__init__.py
 create mode 100644 scripts/kconfig/tests/warn_num_bounds/config
 create mode 100644 scripts/kconfig/tests/warn_num_bounds/expected_config
 create mode 100644 scripts/kconfig/tests/warn_num_bounds/expected_config_stderr
 create mode 100644 scripts/kconfig/tests/warn_num_bounds/expected_frontend_config
 create mode 100644 scripts/kconfig/tests/warn_num_bounds/expected_frontend_stderr

diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 4234a51d16fd..2227d89d6328 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -354,6 +354,12 @@ static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
 	case S_INT:
 	case S_HEX:
 		if (sym_string_valid(sym, p)) {
+			if (def != S_DEF_AUTO &&
+			    !sym_string_check_bounds(sym, p))
+				/* hex uses 64-bit unsigned integer */
+				conf_warning("value '%s' for %s is outside the 64-bit %s integer bounds",
+					     p, sym->name,
+					     sym->type == S_INT ? "signed" : "unsigned");
 			sym->def[def].val = xstrdup(p);
 			sym->flags |= def_flags;
 		} else {
diff --git a/scripts/kconfig/lkc_proto.h b/scripts/kconfig/lkc_proto.h
index 8914b4e8f2a8..8b436c87ba4a 100644
--- a/scripts/kconfig/lkc_proto.h
+++ b/scripts/kconfig/lkc_proto.h
@@ -31,6 +31,7 @@ bool sym_set_tristate_value(struct symbol *sym,tristate tri);
 void choice_set_value(struct menu *choice, struct symbol *sym);
 tristate sym_toggle_tristate_value(struct symbol *sym);
 bool sym_string_valid(struct symbol *sym, const char *newval);
+bool sym_string_check_bounds(struct symbol *sym, const char *str);
 bool sym_string_within_range(struct symbol *sym, const char *str);
 bool sym_set_string_value(struct symbol *sym, const char *newval);
 bool sym_is_changeable(const struct symbol *sym);
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 2d8b0c65ce1e..6f99216ee76d 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -4,7 +4,6 @@
  */
 
 #include <ctype.h>
-#include <errno.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
@@ -255,17 +254,13 @@ static int menu_validate_number(struct symbol *sym, struct symbol *sym2,
 		return 1;
 	}
 
-	errno = 0;
-	if (sym->type == S_INT) {
+	if (sym->type == S_INT)
 		type_bounds = "64-bit signed integer";
-		strtoll(sym2->name, NULL, 10);
-	} else {
+	else
 		/* hex */
 		type_bounds = "64-bit unsigned integer";
-		strtoull(sym2->name, NULL, 16);
-	}
 
-	if (errno == ERANGE) {
+	if (!sym_string_check_bounds(sym, sym2->name)) {
 		fprintf(stderr,
 			"%s:%d: error: %s constant '%s' is outside the %s bounds\n",
 			prop->filename, prop->lineno, sym_type_name(sym->type),
diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 7e81b3676ee9..2d1c021fa395 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -5,6 +5,7 @@
 
 #include <sys/types.h>
 #include <ctype.h>
+#include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 #include <regex.h>
@@ -711,6 +712,21 @@ bool sym_string_valid(struct symbol *sym, const char *str)
 	}
 }
 
+bool sym_string_check_bounds(struct symbol *sym, const char *str)
+{
+	errno = 0;
+
+	if (sym->type == S_INT)
+		strtoll(str, NULL, 10);
+	else if (sym->type == S_HEX)
+		strtoull(str, NULL, 16);
+	else
+		/* string */
+		return true;
+
+	return errno != ERANGE;
+}
+
 bool sym_string_within_range(struct symbol *sym, const char *str)
 {
 	struct property *prop;
@@ -722,6 +738,8 @@ bool sym_string_within_range(struct symbol *sym, const char *str)
 	case S_INT:
 		if (!sym_string_valid(sym, str))
 			return false;
+		if (!sym_string_check_bounds(sym, str))
+			return false;
 		prop = sym_get_range_prop(sym);
 		if (!prop)
 			return true;
@@ -731,6 +749,8 @@ bool sym_string_within_range(struct symbol *sym, const char *str)
 	case S_HEX:
 		if (!sym_string_valid(sym, str))
 			return false;
+		if (!sym_string_check_bounds(sym, str))
+			return false;
 		prop = sym_get_range_prop(sym);
 		if (!prop)
 			return true;
diff --git a/scripts/kconfig/tests/warn_num_bounds/Kconfig b/scripts/kconfig/tests/warn_num_bounds/Kconfig
new file mode 100644
index 000000000000..a810225a58a3
--- /dev/null
+++ b/scripts/kconfig/tests/warn_num_bounds/Kconfig
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0
+
+mainmenu "Numeric bounds test"
+
+config INT_TOO_LOW
+	int "Integer below its type bounds"
+
+config INT_TOO_HIGH
+	int "Integer above its type bounds"
+
+config HEX_TOO_HIGH
+	hex "Hex value above its type bounds"
+
+config INT_MIN
+	int "Minimum valid integer"
+
+config INT_MAX
+	int "Maximum valid integer"
+
+config HEX_MIN
+	hex "Minimum valid hex value"
+
+config HEX_MAX
+	hex "Maximum valid hex value"
diff --git a/scripts/kconfig/tests/warn_num_bounds/__init__.py b/scripts/kconfig/tests/warn_num_bounds/__init__.py
new file mode 100644
index 000000000000..db7518258217
--- /dev/null
+++ b/scripts/kconfig/tests/warn_num_bounds/__init__.py
@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0
+"""Test user values outside the numeric type bounds."""
+
+
+def test(conf):
+    in_keys = (
+        '-9223372036854775809\n'
+        '-1\n'
+        '9223372036854775808\n'
+        '1\n'
+        '0x10000000000000000\n'
+        '0x1\n'
+        '-9223372036854775808\n'
+        '9223372036854775807\n'
+        '0x0\n'
+        '0xffffffffffffffff\n'
+    )
+
+    assert conf.oldaskconfig(in_keys=in_keys) == 0
+    assert conf.stderr_matches('expected_frontend_stderr')
+    assert conf.config_matches('expected_frontend_config')
+
+    assert conf.olddefconfig('config') == 0
+    assert conf.stderr_matches('expected_config_stderr')
+    assert conf.config_matches('expected_config')
diff --git a/scripts/kconfig/tests/warn_num_bounds/config b/scripts/kconfig/tests/warn_num_bounds/config
new file mode 100644
index 000000000000..74bf263f99bf
--- /dev/null
+++ b/scripts/kconfig/tests/warn_num_bounds/config
@@ -0,0 +1,7 @@
+CONFIG_INT_TOO_LOW=-9223372036854775809
+CONFIG_INT_TOO_HIGH=9223372036854775808
+CONFIG_HEX_TOO_HIGH=0x10000000000000000
+CONFIG_INT_MIN=-9223372036854775808
+CONFIG_INT_MAX=9223372036854775807
+CONFIG_HEX_MIN=0x0
+CONFIG_HEX_MAX=0xffffffffffffffff
diff --git a/scripts/kconfig/tests/warn_num_bounds/expected_config b/scripts/kconfig/tests/warn_num_bounds/expected_config
new file mode 100644
index 000000000000..8b1aef612bc6
--- /dev/null
+++ b/scripts/kconfig/tests/warn_num_bounds/expected_config
@@ -0,0 +1,11 @@
+#
+# Automatically generated file; DO NOT EDIT.
+# Numeric bounds test
+#
+CONFIG_INT_TOO_LOW=-9223372036854775809
+CONFIG_INT_TOO_HIGH=9223372036854775808
+CONFIG_HEX_TOO_HIGH=0x10000000000000000
+CONFIG_INT_MIN=-9223372036854775808
+CONFIG_INT_MAX=9223372036854775807
+CONFIG_HEX_MIN=0x0
+CONFIG_HEX_MAX=0xffffffffffffffff
diff --git a/scripts/kconfig/tests/warn_num_bounds/expected_config_stderr b/scripts/kconfig/tests/warn_num_bounds/expected_config_stderr
new file mode 100644
index 000000000000..be2ed7fbf648
--- /dev/null
+++ b/scripts/kconfig/tests/warn_num_bounds/expected_config_stderr
@@ -0,0 +1,3 @@
+.config:1:warning: value '-9223372036854775809' for INT_TOO_LOW is outside the 64-bit signed integer bounds
+.config:2:warning: value '9223372036854775808' for INT_TOO_HIGH is outside the 64-bit signed integer bounds
+.config:3:warning: value '0x10000000000000000' for HEX_TOO_HIGH is outside the 64-bit unsigned integer bounds
diff --git a/scripts/kconfig/tests/warn_num_bounds/expected_frontend_config b/scripts/kconfig/tests/warn_num_bounds/expected_frontend_config
new file mode 100644
index 000000000000..a7e842517026
--- /dev/null
+++ b/scripts/kconfig/tests/warn_num_bounds/expected_frontend_config
@@ -0,0 +1,11 @@
+#
+# Automatically generated file; DO NOT EDIT.
+# Numeric bounds test
+#
+CONFIG_INT_TOO_LOW=-1
+CONFIG_INT_TOO_HIGH=1
+CONFIG_HEX_TOO_HIGH=0x1
+CONFIG_INT_MIN=-9223372036854775808
+CONFIG_INT_MAX=9223372036854775807
+CONFIG_HEX_MIN=0x0
+CONFIG_HEX_MAX=0xffffffffffffffff
diff --git a/scripts/kconfig/tests/warn_num_bounds/expected_frontend_stderr b/scripts/kconfig/tests/warn_num_bounds/expected_frontend_stderr
new file mode 100644
index 000000000000..e69de29bb2d1
-- 
2.55.0