1 files changed, 341 insertions, 0 deletions
diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c
new file mode 100644
index 000000000..62516078a
--- /dev/null
+++ b/drivers/misc/lkdtm/heap.c
@@ -0,0 +1,341 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This is for all the tests relating directly to heap memory, including
+ * page allocation and slab allocations.
+ */
+#include "lkdtm.h"
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/sched.h>
+
+static struct kmem_cache *double_free_cache;
+static struct kmem_cache *a_cache;
+static struct kmem_cache *b_cache;
+
+/*
+ * Using volatile here means the compiler cannot ever make assumptions
+ * about this value. This means compile-time length checks involving
+ * this variable cannot be performed; only run-time checks.
+ */
+static volatile int __offset = 1;
+
+/*
+ * If there aren't guard pages, it's likely that a consecutive allocation will
+ * let us overflow into the second allocation without overwriting something real.
+ *
+ * This should always be caught because there is an unconditional unmapped
+ * page after vmap allocations.
+ */
+static void lkdtm_VMALLOC_LINEAR_OVERFLOW(void)
+{
+	char *one, *two;
+
+	one = vzalloc(PAGE_SIZE);
+	two = vzalloc(PAGE_SIZE);
+
+	pr_info("Attempting vmalloc linear overflow ...\n");
+	memset(one, 0xAA, PAGE_SIZE + __offset);
+
+	vfree(two);
+	vfree(one);
+}
+
+/*
+ * This tries to stay within the next largest power-of-2 kmalloc cache
+ * to avoid actually overwriting anything important if it's not detected
+ * correctly.
+ *
+ * This should get caught by either memory tagging, KASan, or by using
+ * CONFIG_SLUB_DEBUG=y and slub_debug=ZF (or CONFIG_SLUB_DEBUG_ON=y).
+ */
+static void lkdtm_SLAB_LINEAR_OVERFLOW(void)
+{
+	size_t len = 1020;
+	u32 *data = kmalloc(len, GFP_KERNEL);
+	if (!data)
+		return;
+
+	pr_info("Attempting slab linear overflow ...\n");
+	OPTIMIZER_HIDE_VAR(data);
+	data[1024 / sizeof(u32)] = 0x12345678;
+	kfree(data);
+}
+
+static void lkdtm_WRITE_AFTER_FREE(void)
+{
+	int *base, *again;
+	size_t len = 1024;
+	/*
+	 * The slub allocator uses the first word to store the free
+	 * pointer in some configurations. Use the middle of the
+	 * allocation to avoid running into the freelist
+	 */
+	size_t offset = (len / sizeof(*base)) / 2;
+
+	base = kmalloc(len, GFP_KERNEL);
+	if (!base)
+		return;
+	pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
+	pr_info("Attempting bad write to freed memory at %p\n",
+		&base[offset]);
+	kfree(base);
+	base[offset] = 0x0abcdef0;
+	/* Attempt to notice the overwrite. */
+	again = kmalloc(len, GFP_KERNEL);
+	kfree(again);
+	if (again != base)
+		pr_info("Hmm, didn't get the same memory range.\n");
+}
+
+static void lkdtm_READ_AFTER_FREE(void)
+{
+	int *base, *val, saw;
+	size_t len = 1024;
+	/*
+	 * The slub allocator will use the either the first word or
+	 * the middle of the allocation to store the free pointer,
+	 * depending on configurations. Store in the second word to
+	 * avoid running into the freelist.
+	 */
+	size_t offset = sizeof(*base);
+
+	base = kmalloc(len, GFP_KERNEL);
+	if (!base) {
+		pr_info("Unable to allocate base memory.\n");
+		return;
+	}
+
+	val = kmalloc(len, GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate val memory.\n");
+		kfree(base);
+		return;
+	}
+
+	*val = 0x12345678;
+	base[offset] = *val;
+	pr_info("Value in memory before free: %x\n", base[offset]);
+
+	kfree(base);
+
+	pr_info("Attempting bad read from freed memory\n");
+	saw = base[offset];
+	if (saw != *val) {
+		/* Good! Poisoning happened, so declare a win. */
+		pr_info("Memory correctly poisoned (%x)\n", saw);
+	} else {
+		pr_err("FAIL: Memory was not poisoned!\n");
+		pr_expected_config_param(CONFIG_INIT_ON_FREE_DEFAULT_ON, "init_on_free");
+	}
+
+	kfree(val);
+}
+
+static void lkdtm_WRITE_BUDDY_AFTER_FREE(void)
+{
+	unsigned long p = __get_free_page(GFP_KERNEL);
+	if (!p) {
+		pr_info("Unable to allocate free page\n");
+		return;
+	}
+
+	pr_info("Writing to the buddy page before free\n");
+	memset((void *)p, 0x3, PAGE_SIZE);
+	free_page(p);
+	schedule();
+	pr_info("Attempting bad write to the buddy page after free\n");
+	memset((void *)p, 0x78, PAGE_SIZE);
+	/* Attempt to notice the overwrite. */
+	p = __get_free_page(GFP_KERNEL);
+	free_page(p);
+	schedule();
+}
+
+static void lkdtm_READ_BUDDY_AFTER_FREE(void)
+{
+	unsigned long p = __get_free_page(GFP_KERNEL);
+	int saw, *val;
+	int *base;
+
+	if (!p) {
+		pr_info("Unable to allocate free page\n");
+		return;
+	}
+
+	val = kmalloc(1024, GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate val memory.\n");
+		free_page(p);
+		return;
+	}
+
+	base = (int *)p;
+
+	*val = 0x12345678;
+	base[0] = *val;
+	pr_info("Value in memory before free: %x\n", base[0]);
+	free_page(p);
+	pr_info("Attempting to read from freed memory\n");
+	saw = base[0];
+	if (saw != *val) {
+		/* Good! Poisoning happened, so declare a win. */
+		pr_info("Memory correctly poisoned (%x)\n", saw);
+	} else {
+		pr_err("FAIL: Buddy page was not poisoned!\n");
+		pr_expected_config_param(CONFIG_INIT_ON_FREE_DEFAULT_ON, "init_on_free");
+	}
+
+	kfree(val);
+}
+
+static 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);
+}
+
+static 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);
+}
+
+static void lkdtm_SLAB_FREE_DOUBLE(void)
+{
+	int *val;
+
+	val = kmem_cache_alloc(double_free_cache, GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate double_free_cache memory.\n");
+		return;
+	}
+
+	/* Just make sure we got real memory. */
+	*val = 0x12345678;
+	pr_info("Attempting double slab free ...\n");
+	kmem_cache_free(double_free_cache, val);
+	kmem_cache_free(double_free_cache, val);
+}
+
+static void lkdtm_SLAB_FREE_CROSS(void)
+{
+	int *val;
+
+	val = kmem_cache_alloc(a_cache, GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate a_cache memory.\n");
+		return;
+	}
+
+	/* Just make sure we got real memory. */
+	*val = 0x12345679;
+	pr_info("Attempting cross-cache slab free ...\n");
+	kmem_cache_free(b_cache, val);
+}
+
+static void lkdtm_SLAB_FREE_PAGE(void)
+{
+	unsigned long p = __get_free_page(GFP_KERNEL);
+
+	pr_info("Attempting non-Slab slab free ...\n");
+	kmem_cache_free(NULL, (void *)p);
+	free_page(p);
+}
+
+/*
+ * We have constructors to keep the caches distinctly separated without
+ * needing to boot with "slab_nomerge".
+ */
+static void ctor_double_free(void *region)
+{ }
+static void ctor_a(void *region)
+{ }
+static void ctor_b(void *region)
+{ }
+
+void __init lkdtm_heap_init(void)
+{
+	double_free_cache = kmem_cache_create("lkdtm-heap-double_free",
+					      64, 0, 0, ctor_double_free);
+	a_cache = kmem_cache_create("lkdtm-heap-a", 64, 0, 0, ctor_a);
+	b_cache = kmem_cache_create("lkdtm-heap-b", 64, 0, 0, ctor_b);
+}
+
+void __exit lkdtm_heap_exit(void)
+{
+	kmem_cache_destroy(double_free_cache);
+	kmem_cache_destroy(a_cache);
+	kmem_cache_destroy(b_cache);
+}
+
+static struct crashtype crashtypes[] = {
+	CRASHTYPE(SLAB_LINEAR_OVERFLOW),
+	CRASHTYPE(VMALLOC_LINEAR_OVERFLOW),
+	CRASHTYPE(WRITE_AFTER_FREE),
+	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),
+};
+
+struct crashtype_category heap_crashtypes = {
+	.crashtypes = crashtypes,
+	.len	    = ARRAY_SIZE(crashtypes),
+};