livepatch: add module locking around kallsyms calls

[sfrench/cifs-2.6.git] / kernel / livepatch / core.c

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 3f9f1d6b4c2e5726217556a40454c46dbe368b89..9ec555732f1a9601ce3733bcd232bb15f4d9ce6f 100644 (file)
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -179,7 +179,9 @@ static int klp_find_object_symbol(const char *objname, const char *name,
                .count = 0
        };
 
+       mutex_lock(&module_mutex);
        kallsyms_on_each_symbol(klp_find_callback, &args);
+       mutex_unlock(&module_mutex);
 
        if (args.count == 0)
                pr_err("symbol '%s' not found in symbol table\n", name);
@@ -219,13 +221,19 @@ static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr)
                .name = name,
                .addr = addr,
        };
+       int ret;
 
-       if (kallsyms_on_each_symbol(klp_verify_callback, &args))
-               return 0;
+       mutex_lock(&module_mutex);
+       ret = kallsyms_on_each_symbol(klp_verify_callback, &args);
+       mutex_unlock(&module_mutex);
 
-       pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
-               name, addr);
-       return -EINVAL;
+       if (!ret) {
+               pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
+                       name, addr);
+               return -EINVAL;
+       }
+
+       return 0;
 }
 
 static int klp_find_verify_func_addr(struct klp_object *obj,
@@ -335,32 +343,20 @@ unlock:
        rcu_read_unlock();
 }
 
-static int klp_disable_func(struct klp_func *func)
+static void klp_disable_func(struct klp_func *func)
 {
        struct klp_ops *ops;
-       int ret;
-
-       if (WARN_ON(func->state != KLP_ENABLED))
-               return -EINVAL;
 
-       if (WARN_ON(!func->old_addr))
-               return -EINVAL;
+       WARN_ON(func->state != KLP_ENABLED);
+       WARN_ON(!func->old_addr);
 
        ops = klp_find_ops(func->old_addr);
        if (WARN_ON(!ops))
-               return -EINVAL;
+               return;
 
        if (list_is_singular(&ops->func_stack)) {
-               ret = unregister_ftrace_function(&ops->fops);
-               if (ret) {
-                       pr_err("failed to unregister ftrace handler for function '%s' (%d)\n",
-                              func->old_name, ret);
-                       return ret;
-               }
-
-               ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0);
-               if (ret)
-                       pr_warn("function unregister succeeded but failed to clear the filter\n");
+               WARN_ON(unregister_ftrace_function(&ops->fops));
+               WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));
 
                list_del_rcu(&func->stack_node);
                list_del(&ops->node);
@@ -370,8 +366,6 @@ static int klp_disable_func(struct klp_func *func)
        }
 
        func->state = KLP_DISABLED;
-
-       return 0;
 }
 
 static int klp_enable_func(struct klp_func *func)
@@ -432,23 +426,15 @@ err:
        return ret;
 }
 
-static int klp_disable_object(struct klp_object *obj)
+static void klp_disable_object(struct klp_object *obj)
 {
        struct klp_func *func;
-       int ret;
-
-       for (func = obj->funcs; func->old_name; func++) {
-               if (func->state != KLP_ENABLED)
-                       continue;
 
-               ret = klp_disable_func(func);
-               if (ret)
-                       return ret;
-       }
+       for (func = obj->funcs; func->old_name; func++)
+               if (func->state == KLP_ENABLED)
+                       klp_disable_func(func);
 
        obj->state = KLP_DISABLED;
-
-       return 0;
 }
 
 static int klp_enable_object(struct klp_object *obj)
@@ -464,22 +450,19 @@ static int klp_enable_object(struct klp_object *obj)
 
        for (func = obj->funcs; func->old_name; func++) {
                ret = klp_enable_func(func);
-               if (ret)
-                       goto unregister;
+               if (ret) {
+                       klp_disable_object(obj);
+                       return ret;
+               }
        }
        obj->state = KLP_ENABLED;
 
        return 0;
-
-unregister:
-       WARN_ON(klp_disable_object(obj));
-       return ret;
 }
 
 static int __klp_disable_patch(struct klp_patch *patch)
 {
        struct klp_object *obj;
-       int ret;
 
        /* enforce stacking: only the last enabled patch can be disabled */
        if (!list_is_last(&patch->list, &klp_patches) &&
@@ -489,12 +472,8 @@ static int __klp_disable_patch(struct klp_patch *patch)
        pr_notice("disabling patch '%s'\n", patch->mod->name);
 
        for (obj = patch->objs; obj->funcs; obj++) {
-               if (obj->state != KLP_ENABLED)
-                       continue;
-
-               ret = klp_disable_object(obj);
-               if (ret)
-                       return ret;
+               if (obj->state == KLP_ENABLED)
+                       klp_disable_object(obj);
        }
 
        patch->state = KLP_DISABLED;
@@ -553,8 +532,6 @@ static int __klp_enable_patch(struct klp_patch *patch)
        pr_notice("enabling patch '%s'\n", patch->mod->name);
 
        for (obj = patch->objs; obj->funcs; obj++) {
-               klp_find_object_module(obj);
-
                if (!klp_is_object_loaded(obj))
                        continue;
 
@@ -945,7 +922,6 @@ static void klp_module_notify_going(struct klp_patch *patch,
 {
        struct module *pmod = patch->mod;
        struct module *mod = obj->mod;
-       int ret;
 
        if (patch->state == KLP_DISABLED)
                goto disabled;
@@ -953,10 +929,7 @@ static void klp_module_notify_going(struct klp_patch *patch,
        pr_notice("reverting patch '%s' on unloading module '%s'\n",
                  pmod->name, mod->name);
 
-       ret = klp_disable_object(obj);
-       if (ret)
-               pr_warn("failed to revert patch '%s' on module '%s' (%d)\n",
-                       pmod->name, mod->name, ret);
+       klp_disable_object(obj);
 
 disabled:
        klp_free_object_loaded(obj);