linux-kernel - [PATCH 5.2 100/137] livepatch: Nullify obj->mod in klp_module

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Message-Id: <20191006171217.241438193@linuxfoundation.org>
Date:   Sun,  6 Oct 2019 19:21:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.2 100/137] 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 c4ce08f43bd63..ab4a4606d19b7 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1175,6 +1175,7 @@ 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;
+	obj->mod = NULL;
 	klp_cleanup_module_patches_limited(mod, patch);
 	mutex_unlock(&klp_mutex);
 
-- 
2.20.1