livepatch: unpatch all klp_objects if klp_module_coming fails

When an incoming module is considered for livepatching by
klp_module_coming(), it iterates over multiple patches and multiple
kernel objects in this order:

	list_for_each_entry(patch, &klp_patches, list) {
		klp_for_each_object(patch, obj) {

which means that if one of the kernel objects fails to patch,
klp_module_coming()'s error path needs to unpatch and cleanup any kernel
objects that were already patched by a previous patch.

Reported-by: Miroslav Benes <mbenes@suse.cz>
Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 37 insertions, 23 deletions

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index b9628e43c78f..bf8c8fd72589 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -830,6 +830,41 @@ int klp_register_patch(struct klp_patch *patch)
 }
 EXPORT_SYMBOL_GPL(klp_register_patch);
 
+/*
+ * Remove parts of patches that touch a given kernel module. The list of
+ * patches processed might be limited. When limit is NULL, all patches
+ * will be handled.
+ */
+static void klp_cleanup_module_patches_limited(struct module *mod,
+                                               struct klp_patch *limit)
+{
+        struct klp_patch *patch;
+        struct klp_object *obj;
+
+        list_for_each_entry(patch, &klp_patches, list) {
+                if (patch == limit)
+                        break;
+
+                klp_for_each_object(patch, obj) {
+                        if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
+                                continue;
+
+                        /*
+                         * Only unpatch the module if the patch is enabled or
+                         * is in transition.
+                         */
+                        if (patch->enabled || patch == klp_transition_patch) {
+                                pr_notice("reverting patch '%s' on unloading module '%s'\n",
+                                          patch->mod->name, obj->mod->name);
+                                klp_unpatch_object(obj);
+                        }
+
+                        klp_free_object_loaded(obj);
+                        break;
+                }
+        }
+}
+
 int klp_module_coming(struct module *mod)
 {
         int ret;
@@ -894,7 +929,7 @@ err:
         pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
                 patch->mod->name, obj->mod->name, obj->mod->name);
         mod->klp_alive = false;
-        klp_free_object_loaded(obj);
+        klp_cleanup_module_patches_limited(mod, patch);
         mutex_unlock(&klp_mutex);
 
         return ret;
@@ -902,9 +937,6 @@ err:
 
 void klp_module_going(struct module *mod)
 {
-        struct klp_patch *patch;
-        struct klp_object *obj;
-
         if (WARN_ON(mod->state != MODULE_STATE_GOING &&
                     mod->state != MODULE_STATE_COMING))
                 return;
@@ -917,25 +949,7 @@ void klp_module_going(struct module *mod)
          */
         mod->klp_alive = false;
 
-        list_for_each_entry(patch, &klp_patches, list) {
-                klp_for_each_object(patch, obj) {
-                        if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
-                                continue;
-
-                        /*
-                         * Only unpatch the module if the patch is enabled or
-                         * is in transition.
-                         */
-                        if (patch->enabled || patch == klp_transition_patch) {
-                                pr_notice("reverting patch '%s' on unloading module '%s'\n",
-                                          patch->mod->name, obj->mod->name);
-                                klp_unpatch_object(obj);
-                        }
-
-                        klp_free_object_loaded(obj);
-                        break;
-                }
-        }
+        klp_cleanup_module_patches_limited(mod, NULL);
 
         mutex_unlock(&klp_mutex);
 }