[160/166] drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks
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Message ID 20200407031234.-8O1JXJen%akpm@linux-foundation.org
State New
Headers show
Series
  • [001/166] mm, memcg: bypass high reclaim iteration for cgroup hierarchy root
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Commit Message

Andrew Morton April 7, 2020, 3:12 a.m. UTC
From: Kees Cook <keescook@chromium.org>
Subject: drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks

Adds LKDTM tests for arithmetic overflow (both signed and unsigned), as
well as array bounds checking.

Link: http://lkml.kernel.org/r/20200227193516.32566-4-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/misc/lkdtm/bugs.c  |   75 +++++++++++++++++++++++++++++++++++
 drivers/misc/lkdtm/core.c  |    3 +
 drivers/misc/lkdtm/lkdtm.h |    3 +
 3 files changed, 81 insertions(+)

Patch
diff mbox series

--- a/drivers/misc/lkdtm/bugs.c~lkdtm-bugs-add-arithmetic-overflow-and-array-bounds-checks
+++ a/drivers/misc/lkdtm/bugs.c
@@ -11,6 +11,7 @@ 
 #include <linux/sched/signal.h>
 #include <linux/sched/task_stack.h>
 #include <linux/uaccess.h>
+#include <linux/slab.h>
 
 #ifdef CONFIG_X86_32
 #include <asm/desc.h>
@@ -175,6 +176,80 @@  void lkdtm_HUNG_TASK(void)
 	schedule();
 }
 
+volatile unsigned int huge = INT_MAX - 2;
+volatile unsigned int ignored;
+
+void lkdtm_OVERFLOW_SIGNED(void)
+{
+	int value;
+
+	value = huge;
+	pr_info("Normal signed addition ...\n");
+	value += 1;
+	ignored = value;
+
+	pr_info("Overflowing signed addition ...\n");
+	value += 4;
+	ignored = value;
+}
+
+
+void lkdtm_OVERFLOW_UNSIGNED(void)
+{
+	unsigned int value;
+
+	value = huge;
+	pr_info("Normal unsigned addition ...\n");
+	value += 1;
+	ignored = value;
+
+	pr_info("Overflowing unsigned addition ...\n");
+	value += 4;
+	ignored = value;
+}
+
+/* Intentially using old-style flex array definition of 1 byte. */
+struct array_bounds_flex_array {
+	int one;
+	int two;
+	char data[1];
+};
+
+struct array_bounds {
+	int one;
+	int two;
+	char data[8];
+	int three;
+};
+
+void lkdtm_ARRAY_BOUNDS(void)
+{
+	struct array_bounds_flex_array *not_checked;
+	struct array_bounds *checked;
+	volatile int i;
+
+	not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL);
+	checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL);
+
+	pr_info("Array access within bounds ...\n");
+	/* For both, touch all bytes in the actual member size. */
+	for (i = 0; i < sizeof(checked->data); i++)
+		checked->data[i] = 'A';
+	/*
+	 * For the uninstrumented flex array member, also touch 1 byte
+	 * beyond to verify it is correctly uninstrumented.
+	 */
+	for (i = 0; i < sizeof(not_checked->data) + 1; i++)
+		not_checked->data[i] = 'A';
+
+	pr_info("Array access beyond bounds ...\n");
+	for (i = 0; i < sizeof(checked->data) + 1; i++)
+		checked->data[i] = 'B';
+
+	kfree(not_checked);
+	kfree(checked);
+}
+
 void lkdtm_CORRUPT_LIST_ADD(void)
 {
 	/*
--- a/drivers/misc/lkdtm/core.c~lkdtm-bugs-add-arithmetic-overflow-and-array-bounds-checks
+++ a/drivers/misc/lkdtm/core.c
@@ -130,6 +130,9 @@  static const struct crashtype crashtypes
 	CRASHTYPE(HARDLOCKUP),
 	CRASHTYPE(SPINLOCKUP),
 	CRASHTYPE(HUNG_TASK),
+	CRASHTYPE(OVERFLOW_SIGNED),
+	CRASHTYPE(OVERFLOW_UNSIGNED),
+	CRASHTYPE(ARRAY_BOUNDS),
 	CRASHTYPE(EXEC_DATA),
 	CRASHTYPE(EXEC_STACK),
 	CRASHTYPE(EXEC_KMALLOC),
--- a/drivers/misc/lkdtm/lkdtm.h~lkdtm-bugs-add-arithmetic-overflow-and-array-bounds-checks
+++ a/drivers/misc/lkdtm/lkdtm.h
@@ -22,6 +22,9 @@  void lkdtm_SOFTLOCKUP(void);
 void lkdtm_HARDLOCKUP(void);
 void lkdtm_SPINLOCKUP(void);
 void lkdtm_HUNG_TASK(void);
+void lkdtm_OVERFLOW_SIGNED(void);
+void lkdtm_OVERFLOW_UNSIGNED(void);
+void lkdtm_ARRAY_BOUNDS(void);
 void lkdtm_CORRUPT_LIST_ADD(void);
 void lkdtm_CORRUPT_LIST_DEL(void);
 void lkdtm_CORRUPT_USER_DS(void);