lkdtm/heap: Add init_on_alloc tests

Add SLAB and page allocator tests for init_on_alloc. Testing for
init_on_free was already happening via the poisoning tests.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210623203936.3151093-10-keescook@chromium.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/lkdtm/core.c

@@ -127,6 +127,8 @@ static const struct crashtype crashtypes[] = {
 	CRASHTYPE(READ_AFTER_FREE),
 	CRASHTYPE(WRITE_BUDDY_AFTER_FREE),
 	CRASHTYPE(READ_BUDDY_AFTER_FREE),
+	CRASHTYPE(SLAB_INIT_ON_ALLOC),
+	CRASHTYPE(BUDDY_INIT_ON_ALLOC),
 	CRASHTYPE(SLAB_FREE_DOUBLE),
 	CRASHTYPE(SLAB_FREE_CROSS),
 	CRASHTYPE(SLAB_FREE_PAGE),

drivers/misc/lkdtm/heap.c

@@ -174,6 +174,71 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void)
 	kfree(val);
 }
 
+void lkdtm_SLAB_INIT_ON_ALLOC(void)
+{
+	u8 *first;
+	u8 *val;
+
+	first = kmalloc(512, GFP_KERNEL);
+	if (!first) {
+		pr_info("Unable to allocate 512 bytes the first time.\n");
+		return;
+	}
+
+	memset(first, 0xAB, 512);
+	kfree(first);
+
+	val = kmalloc(512, GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate 512 bytes the second time.\n");
+		return;
+	}
+	if (val != first) {
+		pr_warn("Reallocation missed clobbered memory.\n");
+	}
+
+	if (memchr(val, 0xAB, 512) == NULL) {
+		pr_info("Memory appears initialized (%x, no earlier values)\n", *val);
+	} else {
+		pr_err("FAIL: Slab was not initialized\n");
+		pr_expected_config_param(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, "init_on_alloc");
+	}
+	kfree(val);
+}
+
+void lkdtm_BUDDY_INIT_ON_ALLOC(void)
+{
+	u8 *first;
+	u8 *val;
+
+	first = (u8 *)__get_free_page(GFP_KERNEL);
+	if (!first) {
+		pr_info("Unable to allocate first free page\n");
+		return;
+	}
+
+	memset(first, 0xAB, PAGE_SIZE);
+	free_page((unsigned long)first);
+
+	val = (u8 *)__get_free_page(GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate second free page\n");
+		return;
+	}
+
+	if (val != first) {
+		pr_warn("Reallocation missed clobbered memory.\n");
+	}
+
+	if (memchr(val, 0xAB, PAGE_SIZE) == NULL) {
+		pr_info("Memory appears initialized (%x, no earlier values)\n", *val);
+	} else {
+		pr_err("FAIL: Slab was not initialized\n");
+		pr_expected_config_param(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, "init_on_alloc");
+	}
+	free_page((unsigned long)val);
+}
+
 void lkdtm_SLAB_FREE_DOUBLE(void)
 {
 	int *val;

drivers/misc/lkdtm/lkdtm.h

@@ -86,6 +86,8 @@ void lkdtm_WRITE_AFTER_FREE(void);
 void lkdtm_READ_AFTER_FREE(void);
 void lkdtm_WRITE_BUDDY_AFTER_FREE(void);
 void lkdtm_READ_BUDDY_AFTER_FREE(void);
+void lkdtm_SLAB_INIT_ON_ALLOC(void);
+void lkdtm_BUDDY_INIT_ON_ALLOC(void);
 void lkdtm_SLAB_FREE_DOUBLE(void);
 void lkdtm_SLAB_FREE_CROSS(void);
 void lkdtm_SLAB_FREE_PAGE(void);

tools/testing/selftests/lkdtm/config

@@ -5,3 +5,4 @@ CONFIG_FORTIFY_SOURCE=y
 CONFIG_HARDENED_USERCOPY=y
 # CONFIG_HARDENED_USERCOPY_FALLBACK is not set
 CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
+CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y

tools/testing/selftests/lkdtm/tests.txt

@@ -21,6 +21,8 @@ VMALLOC_LINEAR_OVERFLOW
 READ_AFTER_FREE call trace:|Memory correctly poisoned
 #WRITE_BUDDY_AFTER_FREE Corrupts memory on failure
 READ_BUDDY_AFTER_FREE call trace:|Memory correctly poisoned
+SLAB_INIT_ON_ALLOC Memory appears initialized
+BUDDY_INIT_ON_ALLOC Memory appears initialized
 SLAB_FREE_DOUBLE
 SLAB_FREE_CROSS
 SLAB_FREE_PAGE