livepatch: x86: fix relocation computation with kASLR

With kASLR enabled, old_addr provided by patch module is being shifted
accrodingly so that the symbol lookups work. To have module relocations
handled properly as well, the same transformation needs to be perfomed
on relocation address information.

[jkosina@suse.cz: extended / reworded changelog a bit]
Reported-by: Cyril B. <cbay@alwaysdata.com>
Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

kernel/livepatch/core.c

@@ -294,6 +294,12 @@ static int klp_write_object_relocations(struct module *pmod,
 
 	for (reloc = obj->relocs; reloc->name; reloc++) {
 		if (!klp_is_module(obj)) {
+
+#if defined(CONFIG_RANDOMIZE_BASE)
+			/* If KASLR has been enabled, adjust old value accordingly */
+			if (kaslr_enabled())
+				reloc->val += kaslr_offset();
+#endif
 			ret = klp_verify_vmlinux_symbol(reloc->name,
 							reloc->val);
 			if (ret)