* [PATCH v2 1/3] module: Fix freeing of charp module parameters when CONFIG_SYSFS=n
2026-03-13 13:48 [PATCH v2 0/3] module: Fix freeing of charp module parameters when CONFIG_SYSFS=n Petr Pavlu
@ 2026-03-13 13:48 ` Petr Pavlu
2026-03-13 13:48 ` [PATCH v2 2/3] module: Clean up parse_args() arguments Petr Pavlu
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Petr Pavlu @ 2026-03-13 13:48 UTC (permalink / raw)
To: Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen
Cc: Christophe Leroy, Aaron Tomlin, Greg Kroah-Hartman,
Rafael J. Wysocki, Danilo Krummrich, linux-modules, linux-kernel
When setting a charp module parameter, the param_set_charp() function
allocates memory to store a copy of the input value. Later, when the module
is potentially unloaded, the destroy_params() function is called to free
this allocated memory.
However, destroy_params() is available only when CONFIG_SYSFS=y, otherwise
only a dummy variant is present. In the unlikely case that the kernel is
configured with CONFIG_MODULES=y and CONFIG_SYSFS=n, this results in
a memory leak of charp values when a module is unloaded.
Fix this issue by making destroy_params() always available when
CONFIG_MODULES=y. Rename the function to module_destroy_params() to clarify
that it is intended for use by the module loader.
Fixes: e180a6b7759a ("param: fix charp parameters set via sysfs")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
include/linux/moduleparam.h | 11 +++--------
kernel/module/main.c | 4 ++--
kernel/params.c | 27 ++++++++++++++++++---------
3 files changed, 23 insertions(+), 19 deletions(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 7d22d4c4ea2e..8667f72503d9 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -426,14 +426,9 @@ extern char *parse_args(const char *name,
void *arg, parse_unknown_fn unknown);
/* Called by module remove. */
-#ifdef CONFIG_SYSFS
-extern void destroy_params(const struct kernel_param *params, unsigned num);
-#else
-static inline void destroy_params(const struct kernel_param *params,
- unsigned num)
-{
-}
-#endif /* !CONFIG_SYSFS */
+#ifdef CONFIG_MODULES
+void module_destroy_params(const struct kernel_param *params, unsigned int num);
+#endif
/* All the helper functions */
/* The macros to do compile-time type checking stolen from Jakub
diff --git a/kernel/module/main.c b/kernel/module/main.c
index c3ce106c70af..ef2e2130972f 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1408,7 +1408,7 @@ static void free_module(struct module *mod)
module_unload_free(mod);
/* Free any allocated parameters. */
- destroy_params(mod->kp, mod->num_kp);
+ module_destroy_params(mod->kp, mod->num_kp);
if (is_livepatch_module(mod))
free_module_elf(mod);
@@ -3519,7 +3519,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
mod_sysfs_teardown(mod);
coming_cleanup:
mod->state = MODULE_STATE_GOING;
- destroy_params(mod->kp, mod->num_kp);
+ module_destroy_params(mod->kp, mod->num_kp);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
klp_module_going(mod);
diff --git a/kernel/params.c b/kernel/params.c
index 7188a12dbe86..c6a354d54213 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -745,15 +745,6 @@ void module_param_sysfs_remove(struct module *mod)
}
#endif
-void destroy_params(const struct kernel_param *params, unsigned num)
-{
- unsigned int i;
-
- for (i = 0; i < num; i++)
- if (params[i].ops->free)
- params[i].ops->free(params[i].arg);
-}
-
struct module_kobject * __init_or_module
lookup_or_create_module_kobject(const char *name)
{
@@ -985,3 +976,21 @@ static int __init param_sysfs_builtin_init(void)
late_initcall(param_sysfs_builtin_init);
#endif /* CONFIG_SYSFS */
+
+#ifdef CONFIG_MODULES
+
+/*
+ * module_destroy_params - free all parameters for one module
+ * @params: module parameters (array)
+ * @num: number of module parameters
+ */
+void module_destroy_params(const struct kernel_param *params, unsigned int num)
+{
+ unsigned int i;
+
+ for (i = 0; i < num; i++)
+ if (params[i].ops->free)
+ params[i].ops->free(params[i].arg);
+}
+
+#endif /* CONFIG_MODULES */
--
2.53.0
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v2 2/3] module: Clean up parse_args() arguments
2026-03-13 13:48 [PATCH v2 0/3] module: Fix freeing of charp module parameters when CONFIG_SYSFS=n Petr Pavlu
2026-03-13 13:48 ` [PATCH v2 1/3] " Petr Pavlu
@ 2026-03-13 13:48 ` Petr Pavlu
2026-03-13 13:48 ` [PATCH v2 3/3] module: Remove extern keyword from param prototypes Petr Pavlu
2026-03-20 17:45 ` [PATCH v2 0/3] module: Fix freeing of charp module parameters when CONFIG_SYSFS=n Sami Tolvanen
3 siblings, 0 replies; 5+ messages in thread
From: Petr Pavlu @ 2026-03-13 13:48 UTC (permalink / raw)
To: Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen
Cc: Christophe Leroy, Aaron Tomlin, Greg Kroah-Hartman,
Rafael J. Wysocki, Danilo Krummrich, linux-modules, linux-kernel
* Use the preferred `unsigned int` over plain `unsigned` for the `num`
parameter.
* Synchronize the parameter names in moduleparam.h with the ones used by
the implementation in params.c.
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
include/linux/moduleparam.h | 8 ++++----
kernel/params.c | 2 +-
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 8667f72503d9..604bc6e9f3a1 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -417,12 +417,12 @@ extern bool parameqn(const char *name1, const char *name2, size_t n);
typedef int (*parse_unknown_fn)(char *param, char *val, const char *doing, void *arg);
/* Called on module insert or kernel boot */
-extern char *parse_args(const char *name,
+extern char *parse_args(const char *doing,
char *args,
const struct kernel_param *params,
- unsigned num,
- s16 level_min,
- s16 level_max,
+ unsigned int num,
+ s16 min_level,
+ s16 max_level,
void *arg, parse_unknown_fn unknown);
/* Called by module remove. */
diff --git a/kernel/params.c b/kernel/params.c
index c6a354d54213..74d620bc2521 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -161,7 +161,7 @@ static int parse_one(char *param,
char *parse_args(const char *doing,
char *args,
const struct kernel_param *params,
- unsigned num,
+ unsigned int num,
s16 min_level,
s16 max_level,
void *arg, parse_unknown_fn unknown)
--
2.53.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2 3/3] module: Remove extern keyword from param prototypes
2026-03-13 13:48 [PATCH v2 0/3] module: Fix freeing of charp module parameters when CONFIG_SYSFS=n Petr Pavlu
2026-03-13 13:48 ` [PATCH v2 1/3] " Petr Pavlu
2026-03-13 13:48 ` [PATCH v2 2/3] module: Clean up parse_args() arguments Petr Pavlu
@ 2026-03-13 13:48 ` Petr Pavlu
2026-03-20 17:45 ` [PATCH v2 0/3] module: Fix freeing of charp module parameters when CONFIG_SYSFS=n Sami Tolvanen
3 siblings, 0 replies; 5+ messages in thread
From: Petr Pavlu @ 2026-03-13 13:48 UTC (permalink / raw)
To: Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen
Cc: Christophe Leroy, Aaron Tomlin, Greg Kroah-Hartman,
Rafael J. Wysocki, Danilo Krummrich, linux-modules, linux-kernel
The external function declarations do not need the "extern" keyword. Remove
it to align with the Linux kernel coding style and to silence the
associated checkpatch warnings.
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
include/linux/moduleparam.h | 89 ++++++++++++++++++-------------------
1 file changed, 44 insertions(+), 45 deletions(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 604bc6e9f3a1..075f28585074 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -317,8 +317,8 @@ struct kparam_array
name, &__param_ops_##name, arg, perm, -1, 0)
#ifdef CONFIG_SYSFS
-extern void kernel_param_lock(struct module *mod);
-extern void kernel_param_unlock(struct module *mod);
+void kernel_param_lock(struct module *mod);
+void kernel_param_unlock(struct module *mod);
#else
static inline void kernel_param_lock(struct module *mod)
{
@@ -398,7 +398,7 @@ static inline void kernel_param_unlock(struct module *mod)
* Returns: true if the two parameter names are equal.
* Dashes (-) are considered equal to underscores (_).
*/
-extern bool parameq(const char *name1, const char *name2);
+bool parameq(const char *name1, const char *name2);
/**
* parameqn - checks if two parameter names match
@@ -412,18 +412,18 @@ extern bool parameq(const char *name1, const char *name2);
* are equal.
* Dashes (-) are considered equal to underscores (_).
*/
-extern bool parameqn(const char *name1, const char *name2, size_t n);
+bool parameqn(const char *name1, const char *name2, size_t n);
typedef int (*parse_unknown_fn)(char *param, char *val, const char *doing, void *arg);
/* Called on module insert or kernel boot */
-extern char *parse_args(const char *doing,
- char *args,
- const struct kernel_param *params,
- unsigned int num,
- s16 min_level,
- s16 max_level,
- void *arg, parse_unknown_fn unknown);
+char *parse_args(const char *doing,
+ char *args,
+ const struct kernel_param *params,
+ unsigned int num,
+ s16 min_level,
+ s16 max_level,
+ void *arg, parse_unknown_fn unknown);
/* Called by module remove. */
#ifdef CONFIG_MODULES
@@ -437,78 +437,77 @@ void module_destroy_params(const struct kernel_param *params, unsigned int num);
static inline type __always_unused *__check_##name(void) { return(p); }
extern const struct kernel_param_ops param_ops_byte;
-extern int param_set_byte(const char *val, const struct kernel_param *kp);
-extern int param_get_byte(char *buffer, const struct kernel_param *kp);
+int param_set_byte(const char *val, const struct kernel_param *kp);
+int param_get_byte(char *buffer, const struct kernel_param *kp);
#define param_check_byte(name, p) __param_check(name, p, unsigned char)
extern const struct kernel_param_ops param_ops_short;
-extern int param_set_short(const char *val, const struct kernel_param *kp);
-extern int param_get_short(char *buffer, const struct kernel_param *kp);
+int param_set_short(const char *val, const struct kernel_param *kp);
+int param_get_short(char *buffer, const struct kernel_param *kp);
#define param_check_short(name, p) __param_check(name, p, short)
extern const struct kernel_param_ops param_ops_ushort;
-extern int param_set_ushort(const char *val, const struct kernel_param *kp);
-extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
+int param_set_ushort(const char *val, const struct kernel_param *kp);
+int param_get_ushort(char *buffer, const struct kernel_param *kp);
#define param_check_ushort(name, p) __param_check(name, p, unsigned short)
extern const struct kernel_param_ops param_ops_int;
-extern int param_set_int(const char *val, const struct kernel_param *kp);
-extern int param_get_int(char *buffer, const struct kernel_param *kp);
+int param_set_int(const char *val, const struct kernel_param *kp);
+int param_get_int(char *buffer, const struct kernel_param *kp);
#define param_check_int(name, p) __param_check(name, p, int)
extern const struct kernel_param_ops param_ops_uint;
-extern int param_set_uint(const char *val, const struct kernel_param *kp);
-extern int param_get_uint(char *buffer, const struct kernel_param *kp);
+int param_set_uint(const char *val, const struct kernel_param *kp);
+int param_get_uint(char *buffer, const struct kernel_param *kp);
int param_set_uint_minmax(const char *val, const struct kernel_param *kp,
unsigned int min, unsigned int max);
#define param_check_uint(name, p) __param_check(name, p, unsigned int)
extern const struct kernel_param_ops param_ops_long;
-extern int param_set_long(const char *val, const struct kernel_param *kp);
-extern int param_get_long(char *buffer, const struct kernel_param *kp);
+int param_set_long(const char *val, const struct kernel_param *kp);
+int param_get_long(char *buffer, const struct kernel_param *kp);
#define param_check_long(name, p) __param_check(name, p, long)
extern const struct kernel_param_ops param_ops_ulong;
-extern int param_set_ulong(const char *val, const struct kernel_param *kp);
-extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
+int param_set_ulong(const char *val, const struct kernel_param *kp);
+int param_get_ulong(char *buffer, const struct kernel_param *kp);
#define param_check_ulong(name, p) __param_check(name, p, unsigned long)
extern const struct kernel_param_ops param_ops_ullong;
-extern int param_set_ullong(const char *val, const struct kernel_param *kp);
-extern int param_get_ullong(char *buffer, const struct kernel_param *kp);
+int param_set_ullong(const char *val, const struct kernel_param *kp);
+int param_get_ullong(char *buffer, const struct kernel_param *kp);
#define param_check_ullong(name, p) __param_check(name, p, unsigned long long)
extern const struct kernel_param_ops param_ops_hexint;
-extern int param_set_hexint(const char *val, const struct kernel_param *kp);
-extern int param_get_hexint(char *buffer, const struct kernel_param *kp);
+int param_set_hexint(const char *val, const struct kernel_param *kp);
+int param_get_hexint(char *buffer, const struct kernel_param *kp);
#define param_check_hexint(name, p) param_check_uint(name, p)
extern const struct kernel_param_ops param_ops_charp;
-extern int param_set_charp(const char *val, const struct kernel_param *kp);
-extern int param_get_charp(char *buffer, const struct kernel_param *kp);
-extern void param_free_charp(void *arg);
+int param_set_charp(const char *val, const struct kernel_param *kp);
+int param_get_charp(char *buffer, const struct kernel_param *kp);
+void param_free_charp(void *arg);
#define param_check_charp(name, p) __param_check(name, p, char *)
/* We used to allow int as well as bool. We're taking that away! */
extern const struct kernel_param_ops param_ops_bool;
-extern int param_set_bool(const char *val, const struct kernel_param *kp);
-extern int param_get_bool(char *buffer, const struct kernel_param *kp);
+int param_set_bool(const char *val, const struct kernel_param *kp);
+int param_get_bool(char *buffer, const struct kernel_param *kp);
#define param_check_bool(name, p) __param_check(name, p, bool)
extern const struct kernel_param_ops param_ops_bool_enable_only;
-extern int param_set_bool_enable_only(const char *val,
- const struct kernel_param *kp);
+int param_set_bool_enable_only(const char *val, const struct kernel_param *kp);
/* getter is the same as for the regular bool */
#define param_check_bool_enable_only param_check_bool
extern const struct kernel_param_ops param_ops_invbool;
-extern int param_set_invbool(const char *val, const struct kernel_param *kp);
-extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
+int param_set_invbool(const char *val, const struct kernel_param *kp);
+int param_get_invbool(char *buffer, const struct kernel_param *kp);
#define param_check_invbool(name, p) __param_check(name, p, bool)
/* An int, which can only be set like a bool (though it shows as an int). */
extern const struct kernel_param_ops param_ops_bint;
-extern int param_set_bint(const char *val, const struct kernel_param *kp);
+int param_set_bint(const char *val, const struct kernel_param *kp);
#define param_get_bint param_get_int
#define param_check_bint param_check_int
@@ -615,19 +614,19 @@ enum hwparam_type {
extern const struct kernel_param_ops param_array_ops;
extern const struct kernel_param_ops param_ops_string;
-extern int param_set_copystring(const char *val, const struct kernel_param *);
-extern int param_get_string(char *buffer, const struct kernel_param *kp);
+int param_set_copystring(const char *val, const struct kernel_param *kp);
+int param_get_string(char *buffer, const struct kernel_param *kp);
/* for exporting parameters in /sys/module/.../parameters */
struct module;
#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
-extern int module_param_sysfs_setup(struct module *mod,
- const struct kernel_param *kparam,
- unsigned int num_params);
+int module_param_sysfs_setup(struct module *mod,
+ const struct kernel_param *kparam,
+ unsigned int num_params);
-extern void module_param_sysfs_remove(struct module *mod);
+void module_param_sysfs_remove(struct module *mod);
#else
static inline int module_param_sysfs_setup(struct module *mod,
const struct kernel_param *kparam,
--
2.53.0
^ permalink raw reply [flat|nested] 5+ messages in thread