linux-kernel - [PATCH AUTOSEL 4.14 06/23] livepatch: Nullify obj->mod in klp_module

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Date:   Sun, 29 Sep 2019 13:35:16 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Miroslav Benes <mbenes@...e.cz>, Petr Mladek <pmladek@...e.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Sasha Levin <sashal@...nel.org>, live-patching@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 06/23] livepatch: Nullify obj->mod in klp_module_coming()'s error path

From: Miroslav Benes <mbenes@...e.cz>

[ Upstream commit 4ff96fb52c6964ad42e0a878be8f86a2e8052ddd ]

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>
Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/livepatch/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 88754e9790f9b..f8dc77b18962c 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -941,6 +941,7 @@ 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);
 
-- 
2.20.1