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Subject[PATCH 05/12] lkdtm: split heap corruption tests to separate file
Date
This splits the *_AFTER_FREE and related tests into the new lkdtm_heap.c
file to help separate things better for readability.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/misc/Makefile | 1 +
drivers/misc/lkdtm.h | 7 +++
drivers/misc/lkdtm_core.c | 124 ++++-----------------------------------
drivers/misc/lkdtm_heap.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 164 insertions(+), 114 deletions(-)
create mode 100644 drivers/misc/lkdtm_heap.c

diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 9f6e95bc0635..d66f657cf9f2 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_CXL_BASE) += cxl/
obj-$(CONFIG_PANEL) += panel.o

lkdtm-$(CONFIG_LKDTM) += lkdtm_core.o
+lkdtm-$(CONFIG_LKDTM) += lkdtm_heap.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_perms.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_rodata_objcopy.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_usercopy.o
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
index 40f681cd6efe..9397360a2b11 100644
--- a/drivers/misc/lkdtm.h
+++ b/drivers/misc/lkdtm.h
@@ -1,6 +1,13 @@
#ifndef __LKDTM_H
#define __LKDTM_H

+/* lkdtm_heap.c */
+void lkdtm_OVERWRITE_ALLOCATION(void);
+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);
+
/* lkdtm_perms.c */
void __init lkdtm_perms_init(void);
void lkdtm_WRITE_RO(void);
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 0b3e3770068a..1c5056c286c5 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -384,125 +384,21 @@ static void lkdtm_do_action(enum ctype which)
*p = val;
break;
}
- case CT_OVERWRITE_ALLOCATION: {
- size_t len = 1020;
- u32 *data = kmalloc(len, GFP_KERNEL);
-
- data[1024 / sizeof(u32)] = 0x12345678;
- kfree(data);
+ case CT_OVERWRITE_ALLOCATION:
+ lkdtm_OVERWRITE_ALLOCATION();
break;
- }
- case CT_WRITE_AFTER_FREE: {
- 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);
- 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");
-
+ case CT_WRITE_AFTER_FREE:
+ lkdtm_WRITE_AFTER_FREE();
break;
- }
- case CT_READ_AFTER_FREE: {
- int *base, *val, saw;
- 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)
- break;
-
- val = kmalloc(len, GFP_KERNEL);
- if (!val) {
- kfree(base);
- break;
- }
-
- *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);
- BUG();
- }
- pr_info("Memory was not poisoned\n");
-
- kfree(val);
+ case CT_READ_AFTER_FREE:
+ lkdtm_READ_AFTER_FREE();
break;
- }
- case CT_WRITE_BUDDY_AFTER_FREE: {
- unsigned long p = __get_free_page(GFP_KERNEL);
- if (!p)
- break;
- 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();
-
+ case CT_WRITE_BUDDY_AFTER_FREE:
+ lkdtm_WRITE_BUDDY_AFTER_FREE();
break;
- }
- case CT_READ_BUDDY_AFTER_FREE: {
- unsigned long p = __get_free_page(GFP_KERNEL);
- int saw, *val;
- int *base;
-
- if (!p)
- break;
-
- val = kmalloc(1024, GFP_KERNEL);
- if (!val) {
- free_page(p);
- break;
- }
-
- 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);
- BUG();
- }
- pr_info("Buddy page was not poisoned\n");
-
- kfree(val);
+ case CT_READ_BUDDY_AFTER_FREE:
+ lkdtm_READ_BUDDY_AFTER_FREE();
break;
- }
case CT_SOFTLOCKUP:
preempt_disable();
for (;;)
diff --git a/drivers/misc/lkdtm_heap.c b/drivers/misc/lkdtm_heap.c
new file mode 100644
index 000000000000..12f50e8dcbfe
--- /dev/null
+++ b/drivers/misc/lkdtm_heap.c
@@ -0,0 +1,146 @@
+/*
+ * This is for all the tests relating directly to heap memory, including
+ * page allocation and slab allocations.
+ */
+#define pr_fmt(fmt) "lkdtm: " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "lkdtm.h"
+
+/*
+ * 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.
+ */
+void lkdtm_OVERWRITE_ALLOCATION(void)
+{
+ size_t len = 1020;
+ u32 *data = kmalloc(len, GFP_KERNEL);
+
+ data[1024 / sizeof(u32)] = 0x12345678;
+ kfree(data);
+}
+
+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);
+ 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");
+}
+
+void lkdtm_READ_AFTER_FREE(void)
+{
+ int *base, *val, saw;
+ 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) {
+ 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);
+ BUG();
+ }
+ pr_info("Memory was not poisoned\n");
+
+ kfree(val);
+}
+
+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();
+}
+
+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);
+ BUG();
+ }
+ pr_info("Buddy page was not poisoned\n");
+
+ kfree(val);
+}
--
2.7.4
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