linux-kernel - [PATCH 1/2] livepatch: Nullify obj->mod in klp_module

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Message-Id: <20190719122840.15353-2-mbenes@suse.cz>
Date:   Fri, 19 Jul 2019 14:28:39 +0200
From:   Miroslav Benes <mbenes@...e.cz>
To:     jikos@...nel.org, jpoimboe@...hat.com, pmladek@...e.com
Cc:     joe.lawrence@...hat.com, live-patching@...r.kernel.org,
        linux-kernel@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH 1/2] livepatch: Nullify obj->mod in klp_module_coming()'s error path

klp_module_coming() is called for every module appearing in the system.
It sets obj->mod to a patched module for klp_object obj. Unfortunately
it leaves it set even if an error happens later in the function and the
patched module is not allowed to be loaded.

klp_is_object_loaded() uses obj->mod variable and could currently give a
wrong return value. The bug is probably harmless as of now.

Signed-off-by: Miroslav Benes <mbenes@...e.cz>
Reviewed-by: Petr Mladek <pmladek@...e.com>
---
 kernel/livepatch/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index c4ce08f43bd6..ab4a4606d19b 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1175,6 +1175,7 @@ int klp_module_coming(struct module *mod)
 	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;
+	obj->mod = NULL;
 	klp_cleanup_module_patches_limited(mod, patch);
 	mutex_unlock(&klp_mutex);
 
-- 
2.22.0