x86: mark the .rodata section also NX
The .rodata section shouldn't just be read-only,
but also non-executable. This is free since we've broken
up the 2MB page already anyway.
also update test_nx to check for this.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/test_nx.c b/arch/x86/kernel/test_nx.c
index 36c100c..10b8a6f 100644
--- a/arch/x86/kernel/test_nx.c
+++ b/arch/x86/kernel/test_nx.c
@@ -139,7 +139,6 @@
* Until then, don't run them to avoid too many people getting scared
* by the error message
*/
-#if 0
#ifdef CONFIG_DEBUG_RODATA
/* Test 3: Check if the .rodata section is executable */
@@ -152,6 +151,7 @@
}
#endif
+#if 0
/* Test 4: Check if the .data section of a module is executable */
if (test_address(&test_data)) {
printk(KERN_ERR "test_nx: .data section is executable\n");
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 3a98d6f..9b61c75 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -591,10 +591,17 @@
if (end <= start)
return;
- set_memory_ro(start, (end - start) >> PAGE_SHIFT);
printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
(end - start) >> 10);
+ set_memory_ro(start, (end - start) >> PAGE_SHIFT);
+
+ /*
+ * The rodata section (but not the kernel text!) should also be
+ * not-executable.
+ */
+ start = ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
+ set_memory_nx(start, (end - start) >> PAGE_SHIFT);
rodata_test();