[PATCH] kconfig: reject malformed KCONFIG_PROBABILITY values

[PATCH] kconfig: reject malformed KCONFIG_PROBABILITY values

[Dmitrii Tulnov]

randconfig checks the numeric range of each probability but does not
validate where strtol() stops. For example, KCONFIG_PROBABILITY=50% is
accepted as 50:0:0: the '%' is parsed twice as zero. This silently sets
both tristate y/m probabilities to zero, reducing the coverage of random
configuration builds. Empty fields and extra fields are also accepted.

Require each field to contain an integer followed by the end of the
string or a colon introducing another field, with at most three fields.
Preserve the leading whitespace and optional sign accepted by strtol().
Keep the strtol() result as long until the range check so that narrowing
to int cannot turn an out-of-range value into a valid probability.

Add regression tests for malformed and out-of-range values, the supported
probability formats, and the documented empty-value default.

Fixes: e43956e60769 ("kconfig: implement KCONFIG_PROBABILITY for randconfig")
Assisted-by: LLM
Signed-off-by: Dmitrii Tulnov <tulnov.dl@gmail.com>
---
Validation on kbuild-next, x86_64, GCC 13.3.0:
- make testconfig with HOSTCFLAGS=-Werror: 58 passed. With the original
  conf binary: 18 failed, 40 passed; all failures are new regression tests.
- ASan/UBSan at -O1, with leak detection disabled: the same 58 tests passed.
- Both builds passed 1,635 input cases and 440 comparisons with the original
  conf using valid inputs and fixed seeds. Malformed inputs preserved an
  existing .config, including when KCONFIG_ALLCONFIG was set.
- make defconfig, allnoconfig, allmodconfig and valid randconfig passed.
  KCONFIG_PROBABILITY=50% changed from success to the expected error.
- No vmlinux build or boot test; this changes the host configuration tool.
  A 32-bit host build was unavailable because multilib headers were missing.

An AI coding assistant helped find the issue, prepare the fix, description
and tests, and run validation. The requested task was to find and fix a
useful, reproducible Linux bug suitable for a first contribution.

 scripts/kconfig/conf.c                        |  9 +++-
 .../tests/randconfig_probability/Kconfig      | 12 +++++
 .../tests/randconfig_probability/__init__.py  | 54 +++++++++++++++++++
 3 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 scripts/kconfig/tests/randconfig_probability/Kconfig
 create mode 100644 scripts/kconfig/tests/randconfig_probability/__init__.py

diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index fe8ba09b0..fa5dae74e 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -191,7 +191,14 @@ static void conf_set_all_new_symbols(enum conf_def_mode mode)
 		n = 0;
 		while (env && *env) {
 			char *endp;
-			int tmp = strtol(env, &endp, 10);
+			long tmp = strtol(env, &endp, 10);
+
+			if (endp == env || (*endp && *endp != ':') ||
+			    (*endp == ':' && (!endp[1] || n == 2))) {
+				errno = EINVAL;
+				perror("KCONFIG_PROBABILITY");
+				exit(1);
+			}
 
 			if (tmp >= 0 && tmp <= 100) {
 				p[n++] = tmp;
diff --git a/scripts/kconfig/tests/randconfig_probability/Kconfig b/scripts/kconfig/tests/randconfig_probability/Kconfig
new file mode 100644
index 000000000..84f4e5fcc
--- /dev/null
+++ b/scripts/kconfig/tests/randconfig_probability/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config MODULES
+	bool
+	default y
+	modules
+
+config BOOL
+	bool "Bool"
+
+config TRI
+	tristate "Tristate"
diff --git a/scripts/kconfig/tests/randconfig_probability/__init__.py b/scripts/kconfig/tests/randconfig_probability/__init__.py
new file mode 100644
index 000000000..022c7eaf2
--- /dev/null
+++ b/scripts/kconfig/tests/randconfig_probability/__init__.py
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only
+"""Validate KCONFIG_PROBABILITY without changing the supported distributions."""
+
+import pytest
+
+
+@pytest.mark.parametrize('probability', [
+    'invalid', ' ', '50%', '50 ', '0x32', '10 20', '10:20x',
+    '10:20:invalid', '10:20:30x',
+    ':50', '50:', '10::20', '10:20:', '10:20:30:', '10:20:30:40',
+    '-1', '101', '0:101', '0:0:101', '60:41', '0:60:41',
+    '4294967296', '-4294967296',
+    '999999999999999999999999', '-999999999999999999999999',
+])
+def test_invalid(conf, monkeypatch, probability):
+    monkeypatch.setenv('KCONFIG_PROBABILITY', probability)
+
+    assert conf.randconfig(seed=0) == 1
+    assert 'KCONFIG_PROBABILITY:' in conf.stderr
+
+
+@pytest.mark.parametrize('probability, boolean, tristate', [
+    ('0', 'n', 'n'),
+    ('0:0', 'n', 'n'),
+    ('100:0', 'y', 'y'),
+    ('0:100', 'y', 'm'),
+    ('100:0:0', 'y', 'n'),
+    ('0:100:0', 'n', 'y'),
+    ('0:0:100', 'n', 'm'),
+    ('000:000:100', 'n', 'm'),
+    ('+100:0', 'y', 'y'),
+    (' \t100:0', 'y', 'y'),
+    ('0: \t100:0', 'n', 'y'),
+])
+def test_valid(conf, monkeypatch, probability, boolean, tristate):
+    monkeypatch.setenv('KCONFIG_PROBABILITY', probability)
+
+    assert conf.randconfig(seed=0) == 0
+    for symbol, value in [('BOOL', boolean), ('TRI', tristate)]:
+        if value == 'n':
+            expected = '# CONFIG_{} is not set'.format(symbol)
+        else:
+            expected = 'CONFIG_{}={}'.format(symbol, value)
+        assert expected in conf.config.splitlines()
+
+
+def test_empty(conf, monkeypatch):
+    monkeypatch.delenv('KCONFIG_PROBABILITY', raising=False)
+    assert conf.randconfig(seed=0) == 0
+    default_config = conf.config
+
+    monkeypatch.setenv('KCONFIG_PROBABILITY', '')
+    assert conf.randconfig(seed=0) == 0
+    assert conf.config == default_config

base-commit: cee9395acd8043be0644b25c34bfa86623f2b935

Re: [PATCH] kconfig: reject malformed KCONFIG_PROBABILITY values

[Julian Braha]

Hi Dmitrii,

I see that this is your first patch submission. Welcome!
And thank you for reporting this.

On 9/7/26 20:45, Dmitrii Tulnov wrote:
> randconfig checks the numeric range of each probability but does not
> validate where strtol() stops. For example, KCONFIG_PROBABILITY=50% is
> accepted as 50:0:0: the '%' is parsed twice as zero. This silently sets
> both tristate y/m probabilities to zero, reducing the coverage of random
> configuration builds. 

It would be good to note here that 'KCONFIG_PROBABILITY=50' (without the
'%') should be 25:25:50 instead.

> Empty fields and extra fields are also accepted.

Right, in these cases, I think it's reasonable to assume the user made a
typo or other oversight.

> 
> Require each field to contain an integer followed by the end of the
> string or a colon introducing another field, with at most three fields.
> Preserve the leading whitespace and optional sign accepted by strtol().

I disagree with allowing the leading whitespace and sign. The fact that
it's allowed input for strtol() is incidental to us. The intended input
format for Kconfig is:

XX:XX:XX

not:

  XX: +XX:    -XX

> Keep the strtol() result as long until the range check so that narrowing
> to int cannot turn an out-of-range value into a valid probability.
> 
> Add regression tests for malformed and out-of-range values, the supported
> probability formats, and the documented empty-value default.
> 
> Fixes: e43956e60769 ("kconfig: implement KCONFIG_PROBABILITY for randconfig")
> Assisted-by: LLM
> Signed-off-by: Dmitrii Tulnov <tulnov.dl@gmail.com>
> ---
> Validation on kbuild-next, x86_64, GCC 13.3.0:
> - make testconfig with HOSTCFLAGS=-Werror: 58 passed. With the original
>   conf binary: 18 failed, 40 passed; all failures are new regression tests.
> - ASan/UBSan at -O1, with leak detection disabled: the same 58 tests passed.
> - Both builds passed 1,635 input cases and 440 comparisons with the original
>   conf using valid inputs and fixed seeds. Malformed inputs preserved an
>   existing .config, including when KCONFIG_ALLCONFIG was set.
> - make defconfig, allnoconfig, allmodconfig and valid randconfig passed.
>   KCONFIG_PROBABILITY=50% changed from success to the expected error.
> - No vmlinux build or boot test; this changes the host configuration tool.
>   A 32-bit host build was unavailable because multilib headers were missing.
> 
> An AI coding assistant helped find the issue, prepare the fix, description
> and tests, and run validation. The requested task was to find and fix a
> useful, reproducible Linux bug suitable for a first contribution.
> 
>  scripts/kconfig/conf.c                        |  9 +++-
>  .../tests/randconfig_probability/Kconfig      | 12 +++++
>  .../tests/randconfig_probability/__init__.py  | 54 +++++++++++++++++++
>  3 files changed, 74 insertions(+), 1 deletion(-)
>  create mode 100644 scripts/kconfig/tests/randconfig_probability/Kconfig
>  create mode 100644 scripts/kconfig/tests/randconfig_probability/__init__.py
> 
> diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
> index fe8ba09b0..fa5dae74e 100644
> --- a/scripts/kconfig/conf.c
> +++ b/scripts/kconfig/conf.c
> @@ -191,7 +191,14 @@ static void conf_set_all_new_symbols(enum conf_def_mode mode)
>  		n = 0;
>  		while (env && *env) {
>  			char *endp;
> -			int tmp = strtol(env, &endp, 10);
> +			long tmp = strtol(env, &endp, 10);
> +
> +			if (endp == env || (*endp && *endp != ':') ||
> +			    (*endp == ':' && (!endp[1] || n == 2))) {
> +				errno = EINVAL;
> +				perror("KCONFIG_PROBABILITY");
> +				exit(1);

Unfortunately, sometimes users depend on unintended behavior. So I would
prefer to make this a warning for now, and then promote this to an error
later assuming nobody complains.

- Julian Braha

Re: [PATCH] kconfig: reject malformed KCONFIG_PROBABILITY values

[Dmitrii Tulnov]

Hi Julian,

Thank you for the review and for the welcome.

> It would be good to note here that 'KCONFIG_PROBABILITY=50' (without
> the '%') should be 25:25:50 instead.

You're right. The v2 commit message now states explicitly that
KCONFIG_PROBABILITY=50 gives tristate y/m/n probabilities of 25%/25%/50%.
The regression test compares the equivalent inputs 50 and 50:25:25 across
20 fixed seeds.

> I disagree with allowing the leading whitespace and sign.

Agreed. Leading whitespace and signs are now warning-only because they are
accepted by strtol() but outside Kconfig's documented XX:XX:XX format.

> I would prefer to make this a warning for now, and then promote this to an
> error later assuming nobody complains.

The v2 implementation warns about malformed syntax while retaining the
existing parsing behavior for compatibility. Numeric range violations remain
errors.

Thank you again for taking the time to review this.

Best regards,
Dmitrii

[PATCH v2] kconfig: warn about malformed KCONFIG_PROBABILITY values

[Dmitrii Tulnov]

randconfig checks the numeric range of each probability but does not
validate where strtol() stops. For example, KCONFIG_PROBABILITY=50% is
accepted as 50:0:0: the '%' is parsed repeatedly as zero. This silently
sets both tristate y/m probabilities to zero, reducing the coverage of
random configuration builds. Empty fields and extra fields are also
accepted.

Warn when the value does not follow the documented decimal format. Keep
the existing parsing behavior for now so that users depending on these
inputs are not broken; the warning can be promoted to an error later.
The documented one-field value 50 gives tristate y/m/n probabilities of
25%/25%/50%. Leading whitespace and signs are accepted by strtol(), but are
also warned about because they are outside the documented format.
Keep the strtol() result as long until the range check so that narrowing
to int cannot turn an out-of-range value into a valid probability.

Add regression tests for malformed warnings and out-of-range values, the
supported probability formats, and the documented empty-value default.

Fixes: e43956e60769 ("kconfig: implement KCONFIG_PROBABILITY for randconfig")
Assisted-by: LLM
Signed-off-by: Dmitrii Tulnov <tulnov.dl@gmail.com>
---
Changes since v1:
- Warn about malformed values while retaining their previous parsing behavior.
- Treat leading whitespace and signs as warning-only undocumented input.
- Clarify that 50 gives tristate y/m/n probabilities of 25%/25%/50%, and
  compare it with the equivalent input 50:25:25 across 20 fixed seeds.

Validation on kbuild-next, x86_64, GCC 13.3.0:
- make testconfig with HOSTCFLAGS=-Werror: 78 passed. Malformed values now
  produce warnings while preserving the previous parsing behavior; numeric
  range errors remain fatal.
- ASan/UBSan at -O1, with leak detection disabled: the same 78 tests passed.
- The fixed build accepted 916 of 1,635 generated inputs (including
  warning-only malformed values) and rejected 719 numeric range errors.
  It matched the original on 380 documented-input comparisons with fixed
  seeds. Range errors preserved an existing .config, including with
  KCONFIG_ALLCONFIG set.
- make defconfig, allnoconfig, allmodconfig and valid randconfig passed.
  KCONFIG_PROBABILITY=50% now produces a warning and remains compatible.
- No vmlinux build or boot test; this changes the host configuration tool.
  A 32-bit host build was unavailable because multilib headers were missing.

 scripts/kconfig/conf.c                        | 14 +++-
 .../tests/randconfig_probability/Kconfig      | 12 +++
 .../tests/randconfig_probability/__init__.py  | 79 +++++++++++++++++++
 3 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 scripts/kconfig/tests/randconfig_probability/Kconfig
 create mode 100644 scripts/kconfig/tests/randconfig_probability/__init__.py

diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index fe8ba09b0..33e8baf8d 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -186,12 +186,24 @@ static void conf_set_all_new_symbols(enum conf_def_mode mode)
 
 	if (mode == def_random) {
 		int n, p[3];
+		bool warned = false;
 		char *env = getenv("KCONFIG_PROBABILITY");
 
 		n = 0;
 		while (env && *env) {
 			char *endp;
-			int tmp = strtol(env, &endp, 10);
+			long tmp = strtol(env, &endp, 10);
+
+			if (endp == env || isspace((unsigned char)*env) ||
+			    *env == '+' || *env == '-' ||
+			    (*endp && *endp != ':') ||
+			    (*endp == ':' && (!endp[1] || n == 2))) {
+				if (!warned) {
+					fprintf(stderr,
+						"warning: KCONFIG_PROBABILITY has malformed format\n");
+					warned = true;
+				}
+			}
 
 			if (tmp >= 0 && tmp <= 100) {
 				p[n++] = tmp;
diff --git a/scripts/kconfig/tests/randconfig_probability/Kconfig b/scripts/kconfig/tests/randconfig_probability/Kconfig
new file mode 100644
index 000000000..84f4e5fcc
--- /dev/null
+++ b/scripts/kconfig/tests/randconfig_probability/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config MODULES
+	bool
+	default y
+	modules
+
+config BOOL
+	bool "Bool"
+
+config TRI
+	tristate "Tristate"
diff --git a/scripts/kconfig/tests/randconfig_probability/__init__.py b/scripts/kconfig/tests/randconfig_probability/__init__.py
new file mode 100644
index 000000000..ff1770608
--- /dev/null
+++ b/scripts/kconfig/tests/randconfig_probability/__init__.py
@@ -0,0 +1,79 @@
+# SPDX-License-Identifier: GPL-2.0-only
+"""Validate KCONFIG_PROBABILITY without changing the supported distributions."""
+
+import pytest
+
+
+@pytest.mark.parametrize('probability', [
+    'invalid', ' ', '50%', '50 ', '0x32', '10 20', '10:20x',
+    '10:20:invalid', '10:20:30x',
+    ':50', '50:', '10::20', '10:20:', '10:20:30:', '10:20:30:40',
+    '+100:0', ' \t100:0', '0: \t100:0',
+])
+def test_malformed_warns(conf, monkeypatch, probability):
+    monkeypatch.setenv('KCONFIG_PROBABILITY', probability)
+
+    assert conf.randconfig(seed=0) == 0
+    assert 'warning: KCONFIG_PROBABILITY has malformed format' in conf.stderr
+    assert conf.config is not None
+
+
+@pytest.mark.parametrize('probability', [
+    '-1', '101', '0:101', '0:0:101', '60:41', '0:60:41',
+    '4294967296', '-4294967296',
+    '999999999999999999999999', '-999999999999999999999999',
+])
+def test_out_of_range(conf, monkeypatch, probability):
+    monkeypatch.setenv('KCONFIG_PROBABILITY', probability)
+
+    assert conf.randconfig(seed=0) == 1
+    assert 'KCONFIG_PROBABILITY:' in conf.stderr
+
+
+@pytest.mark.parametrize('probability, boolean, tristate', [
+    ('0', 'n', 'n'),
+    ('0:0', 'n', 'n'),
+    ('100:0', 'y', 'y'),
+    ('0:100', 'y', 'm'),
+    ('100:0:0', 'y', 'n'),
+    ('0:100:0', 'n', 'y'),
+    ('0:0:100', 'n', 'm'),
+    ('000:000:100', 'n', 'm'),
+])
+def test_valid(conf, monkeypatch, probability, boolean, tristate):
+    monkeypatch.setenv('KCONFIG_PROBABILITY', probability)
+
+    assert conf.randconfig(seed=0) == 0
+    assert 'warning:' not in conf.stderr
+    for symbol, value in [('BOOL', boolean), ('TRI', tristate)]:
+        if value == 'n':
+            expected = '# CONFIG_{} is not set'.format(symbol)
+        else:
+            expected = 'CONFIG_{}={}'.format(symbol, value)
+        assert expected in conf.config.splitlines()
+
+
+@pytest.mark.parametrize('seed', range(20))
+def test_single_probability_matches_tristate_split(conf, monkeypatch, seed):
+    monkeypatch.setenv('KCONFIG_PROBABILITY', '50')
+    assert conf.randconfig(seed=seed) == 0
+    assert 'warning:' not in conf.stderr
+    single = conf.config
+
+    # 50% boolean y; 25% tristate y, 25% m, and 50% n.
+    monkeypatch.setenv('KCONFIG_PROBABILITY', '50:25:25')
+    assert conf.randconfig(seed=seed) == 0
+    assert 'warning:' not in conf.stderr
+    assert conf.config == single
+
+
+def test_empty(conf, monkeypatch):
+    monkeypatch.delenv('KCONFIG_PROBABILITY', raising=False)
+    assert conf.randconfig(seed=0) == 0
+    assert 'warning:' not in conf.stderr
+    default_config = conf.config
+
+    monkeypatch.setenv('KCONFIG_PROBABILITY', '')
+    assert conf.randconfig(seed=0) == 0
+    assert 'warning:' not in conf.stderr
+    assert conf.config == default_config

base-commit: cee9395acd8043be0644b25c34bfa86623f2b935

Re: [PATCH v2] kconfig: warn about malformed KCONFIG_PROBABILITY values

[Julian Braha]

Hi Dmitrii,

On 9/8/26 21:36, Dmitrii Tulnov wrote:
> randconfig checks the numeric range of each probability but does not
> validate where strtol() stops. For example, KCONFIG_PROBABILITY=50% is
> accepted as 50:0:0: the '%' is parsed repeatedly as zero. This silently
> sets both tristate y/m probabilities to zero, reducing the coverage of
> random configuration builds. Empty fields and extra fields are also
> accepted.
> 
> Warn when the value does not follow the documented decimal format. Keep
> the existing parsing behavior for now so that users depending on these
> inputs are not broken; the warning can be promoted to an error later.
> The documented one-field value 50 gives tristate y/m/n probabilities of
> 25%/25%/50%. Leading whitespace and signs are accepted by strtol(), but are

This "25:25:50" explanation belongs in the first paragraph where you
give the background and state that "KCONFIG_PROBABILITY=50% is accepted
as 50:0:0". Your second paragraph is about what you're changing.

> also warned about because they are outside the documented format.
> Keep the strtol() result as long until the range check so that narrowing
> to int cannot turn an out-of-range value into a valid probability.
> 
> Add regression tests for malformed warnings and out-of-range values, the
> supported probability formats, and the documented empty-value default.
> 
> Fixes: e43956e60769 ("kconfig: implement KCONFIG_PROBABILITY for randconfig")
> Assisted-by: LLM
> Signed-off-by: Dmitrii Tulnov <tulnov.dl@gmail.com>
> ---
> Changes since v1:
> - Warn about malformed values while retaining their previous parsing behavior.
> - Treat leading whitespace and signs as warning-only undocumented input.
> - Clarify that 50 gives tristate y/m/n probabilities of 25%/25%/50%, and
>   compare it with the equivalent input 50:25:25 across 20 fixed seeds.
> 
> Validation on kbuild-next, x86_64, GCC 13.3.0:
> - make testconfig with HOSTCFLAGS=-Werror: 78 passed. Malformed values now
>   produce warnings while preserving the previous parsing behavior; numeric
>   range errors remain fatal.
> - ASan/UBSan at -O1, with leak detection disabled: the same 78 tests passed.
> - The fixed build accepted 916 of 1,635 generated inputs (including
>   warning-only malformed values) and rejected 719 numeric range errors.
>   It matched the original on 380 documented-input comparisons with fixed
>   seeds. Range errors preserved an existing .config, including with
>   KCONFIG_ALLCONFIG set.
> - make defconfig, allnoconfig, allmodconfig and valid randconfig passed.
>   KCONFIG_PROBABILITY=50% now produces a warning and remains compatible.
> - No vmlinux build or boot test; this changes the host configuration tool.
>   A 32-bit host build was unavailable because multilib headers were missing.
> 
>  scripts/kconfig/conf.c                        | 14 +++-
>  .../tests/randconfig_probability/Kconfig      | 12 +++
>  .../tests/randconfig_probability/__init__.py  | 79 +++++++++++++++++++
>  3 files changed, 104 insertions(+), 1 deletion(-)
>  create mode 100644 scripts/kconfig/tests/randconfig_probability/Kconfig
>  create mode 100644 scripts/kconfig/tests/randconfig_probability/__init__.py
> 
> diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
> index fe8ba09b0..33e8baf8d 100644
> --- a/scripts/kconfig/conf.c
> +++ b/scripts/kconfig/conf.c
> @@ -186,12 +186,24 @@ static void conf_set_all_new_symbols(enum conf_def_mode mode)
>  
>  	if (mode == def_random) {
>  		int n, p[3];
> +		bool warned = false;
>  		char *env = getenv("KCONFIG_PROBABILITY");
>  
>  		n = 0;
>  		while (env && *env) {
>  			char *endp;
> -			int tmp = strtol(env, &endp, 10);
> +			long tmp = strtol(env, &endp, 10);
> +
> +			if (endp == env || isspace((unsigned char)*env) ||
> +			    *env == '+' || *env == '-' ||

This condition expression is pretty long. You can simplify this:

  endp == env || isspace((unsigned char)*env) ||
  *env == '+' || *env == '-'

into:

  !isdigit((unsigned char)*env)

> +			    (*endp && *endp != ':') ||
> +			    (*endp == ':' && (!endp[1] || n == 2))) {
> +				if (!warned) {
> +					fprintf(stderr,
> +						"warning: KCONFIG_PROBABILITY has malformed format\n");
> +					warned = true;
> +				}
> +			}
>  
>  			if (tmp >= 0 && tmp <= 100) {
>  				p[n++] = tmp;
> diff --git a/scripts/kconfig/tests/randconfig_probability/Kconfig b/scripts/kconfig/tests/randconfig_probability/Kconfig
> new file mode 100644
> index 000000000..84f4e5fcc
> --- /dev/null
> +++ b/scripts/kconfig/tests/randconfig_probability/Kconfig
> @@ -0,0 +1,12 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +config MODULES
> +	bool
> +	default y
> +	modules
> +
> +config BOOL
> +	bool "Bool"
> +
> +config TRI
> +	tristate "Tristate"
> diff --git a/scripts/kconfig/tests/randconfig_probability/__init__.py b/scripts/kconfig/tests/randconfig_probability/__init__.py
> new file mode 100644
> index 000000000..ff1770608
> --- /dev/null
> +++ b/scripts/kconfig/tests/randconfig_probability/__init__.py
> @@ -0,0 +1,79 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +"""Validate KCONFIG_PROBABILITY without changing the supported distributions."""
> +
> +import pytest
> +
> +
> +@pytest.mark.parametrize('probability', [
> +    'invalid', ' ', '50%', '50 ', '0x32', '10 20', '10:20x',
> +    '10:20:invalid', '10:20:30x',
> +    ':50', '50:', '10::20', '10:20:', '10:20:30:', '10:20:30:40',
> +    '+100:0', ' \t100:0', '0: \t100:0',
> +])
> +def test_malformed_warns(conf, monkeypatch, probability):
> +    monkeypatch.setenv('KCONFIG_PROBABILITY', probability)

You should set the environment variables using 'conf._run_conf' instead
of 'monkeypatch.setenv'.

For an example, see the test in:
scripts/kconfig/tests/warn_changed_input/
and how it uses 'extra_env'.

> +
> +    assert conf.randconfig(seed=0) == 0
> +    assert 'warning: KCONFIG_PROBABILITY has malformed format' in conf.stderr
> +    assert conf.config is not None
> +
> +
> +@pytest.mark.parametrize('probability', [
> +    '-1', '101', '0:101', '0:0:101', '60:41', '0:60:41',
> +    '4294967296', '-4294967296',
> +    '999999999999999999999999', '-999999999999999999999999',

It would be good to include '-0', which is the only negative input
accepted before this patch.

Also you should include an instance with '+'.

- Julian Braha