[PATCH] livepatch: x86: bugfix about kASLR

From: Zhou Chengming <zhouchengming1@huawei.com>
To: <jpoimboe@redhat.com>, <sjenning@redhat.com>, <jkosina@suse.cz>,
	<vojtech@suse.cz>
Cc: <live-patching@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<guohanjun@huawei.com>, <huawei.libin@huawei.com>,
	<xiexiuqi@huawei.com>, <cbay@alwaysdata.com>
Subject: [PATCH] livepatch: x86: bugfix about kASLR
Date: Wed, 4 Nov 2015 17:32:12 +0800	[thread overview]
Message-ID: <1446629532-32111-1-git-send-email-zhouchengming1@huawei.com> (raw)

When enable KASLR, func->old_addr will be set to zero
and livepatch will find the right old address.
But for reloc, livepatch just verify it using reloc->val
(old addr from user), so verify failed and report
"kernel mismatch" error.

Reported-by: Cyril B. <cbay@alwaysdata.com>
Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
---
 kernel/livepatch/core.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 53196e2..c8885c6 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -311,7 +311,12 @@ static int klp_write_object_relocations(struct module *pmod,
 		return -EINVAL;
 
 	for (reloc = obj->relocs; reloc->name; reloc++) {
-		if (!klp_is_module(obj)) {
+
+#if defined(CONFIG_RANDOMIZE_BASE)
+		/* KASLR is enabled, disregard old_addr from user */
+		reloc->val = 0;
+#endif
+		if (reloc->val && !klp_is_module(obj)) {
 			ret = klp_verify_vmlinux_symbol(reloc->name,
 							reloc->val);
 			if (ret)
-- 
1.7.7

