Enhance the functionality of kpatch to automatically remove the associated
module when replacing an old livepatch with a new one. This ensures that no
leftover modules remain in the system. For instance:
- Load the first livepatch
$ kpatch load 6.9.0-rc1+/livepatch-test_0.ko
loading patch module: 6.9.0-rc1+/livepatch-test_0.ko
waiting (up to 15 seconds) for patch transition to complete...
transition complete (2 seconds)
$ kpatch list
Loaded patch modules:
livepatch_test_0 [enabled]
$ lsmod |grep livepatch
livepatch_test_0 16384 1
- Load a new livepatch
$ kpatch load 6.9.0-rc1+/livepatch-test_1.ko
loading patch module: 6.9.0-rc1+/livepatch-test_1.ko
waiting (up to 15 seconds) for patch transition to complete...
transition complete (2 seconds)
$ kpatch list
Loaded patch modules:
livepatch_test_1 [enabled]
$ lsmod |grep livepatch
livepatch_test_1 16384 1
livepatch_test_0 16384 0 <<<< leftover
With this improvement, executing
`kpatch load 6.9.0-rc1+/livepatch-test_1.ko` will automatically remove the
livepatch-test_0.ko module.
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
include/linux/module.h | 1 +
kernel/livepatch/core.c | 11 +++++++++--
kernel/module/main.c | 43 ++++++++++++++++++++++++-----------------
3 files changed, 35 insertions(+), 20 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h
index 1153b0d99a80..9a95174a919b 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -75,6 +75,7 @@ extern struct module_attribute module_uevent;
/* These are either module local, or the kernel's dummy ones. */
extern int init_module(void);
extern void cleanup_module(void);
+extern void delete_module(struct module *mod);
#ifndef MODULE
/**
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index ecbc9b6aba3a..f1edc999f3ef 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -711,6 +711,8 @@ static void klp_free_patch_start(struct klp_patch *patch)
*/
static void klp_free_patch_finish(struct klp_patch *patch)
{
+ struct module *mod = patch->mod;
+
/*
* Avoid deadlock with enabled_store() sysfs callback by
* calling this outside klp_mutex. It is safe because
@@ -721,8 +723,13 @@ static void klp_free_patch_finish(struct klp_patch *patch)
wait_for_completion(&patch->finish);
/* Put the module after the last access to struct klp_patch. */
- if (!patch->forced)
- module_put(patch->mod);
+ if (!patch->forced) {
+ module_put(mod);
+ if (module_refcount(mod))
+ return;
+ mod->state = MODULE_STATE_GOING;
+ delete_module(mod);
+ }
}
/*
diff --git a/kernel/module/main.c b/kernel/module/main.c
index e1e8a7a9d6c1..e863e1f87dfd 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -695,12 +695,35 @@ EXPORT_SYMBOL(module_refcount);
/* This exists whether we can unload or not */
static void free_module(struct module *mod);
+void delete_module(struct module *mod)
+{
+ char buf[MODULE_FLAGS_BUF_SIZE];
+
+ /* Final destruction now no one is using it. */
+ if (mod->exit != NULL)
+ mod->exit();
+ blocking_notifier_call_chain(&module_notify_list,
+ MODULE_STATE_GOING, mod);
+ klp_module_going(mod);
+ ftrace_release_mod(mod);
+
+ async_synchronize_full();
+
+ /* Store the name and taints of the last unloaded module for diagnostic purposes */
+ strscpy(last_unloaded_module.name, mod->name, sizeof(last_unloaded_module.name));
+ strscpy(last_unloaded_module.taints, module_flags(mod, buf, false),
+ sizeof(last_unloaded_module.taints));
+
+ free_module(mod);
+ /* someone could wait for the module in add_unformed_module() */
+ wake_up_all(&module_wq);
+}
+
SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
unsigned int, flags)
{
struct module *mod;
char name[MODULE_NAME_LEN];
- char buf[MODULE_FLAGS_BUF_SIZE];
int ret, forced = 0;
if (!capable(CAP_SYS_MODULE) || modules_disabled)
@@ -750,23 +773,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
goto out;
mutex_unlock(&module_mutex);
- /* Final destruction now no one is using it. */
- if (mod->exit != NULL)
- mod->exit();
- blocking_notifier_call_chain(&module_notify_list,
- MODULE_STATE_GOING, mod);
- klp_module_going(mod);
- ftrace_release_mod(mod);
-
- async_synchronize_full();
-
- /* Store the name and taints of the last unloaded module for diagnostic purposes */
- strscpy(last_unloaded_module.name, mod->name, sizeof(last_unloaded_module.name));
- strscpy(last_unloaded_module.taints, module_flags(mod, buf, false), sizeof(last_unloaded_module.taints));
-
- free_module(mod);
- /* someone could wait for the module in add_unformed_module() */
- wake_up_all(&module_wq);
+ delete_module(mod);
return 0;
out:
mutex_unlock(&module_mutex);
--
2.39.1
