Le 06/03/2026 à 12:10, Petr Pavlu a écrit :
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 <[email protected]>
---
include/linux/moduleparam.h | 12 ++++--------
kernel/module/main.c | 4 ++--
kernel/params.c | 27 ++++++++++++++++++---------
3 files changed, 24 insertions(+), 19 deletions(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 7d22d4c4ea2e..6283665ec614 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -426,14 +426,10 @@ 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
+extern void module_destroy_params(const struct kernel_param *params,
+ unsigned num);
'extern' is pointless for function prototypes, don't add new ones.
num has no type.
+#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..1a436c9d6140 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 num)
num has no type
+{
+ unsigned int i;
+
+ for (i = 0; i < num; i++)
+ if (params[i].ops->free)
+ params[i].ops->free(params[i].arg);
+}
+
+#endif /* CONFIG_MODULES */
base-commit: c107785c7e8dbabd1c18301a1c362544b5786282
Note, checkpatch reports the same:
CHECK: extern prototypes should be avoided in .h files
#47: FILE: include/linux/moduleparam.h:430:
+extern void module_destroy_params(const struct kernel_param *params,
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
#48: FILE: include/linux/moduleparam.h:431:
+ unsigned num);
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
#107: FILE: kernel/params.c:987:
+void module_destroy_params(const struct kernel_param *params, unsigned num)
total: 0 errors, 2 warnings, 1 checks, 70 lines checked
NOTE: For some of the reported defects, checkpatch may be able to
mechanically convert to the typical style using --fix or
--fix-inplace.
Commit 4aad08ba007a ("module: Fix freeing of charp module parameters
when CONFIG_SYSFS=n") has style problems, please review.
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
Christophe
