lkml.org 
[lkml]   [2020]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v5 3/6] lkdtm/bugs: Add arithmetic overflow and array bounds checks
Date
Adds LKDTM tests for arithmetic overflow (both signed and unsigned),
as well as array bounds checking.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
---
drivers/misc/lkdtm/bugs.c | 75 ++++++++++++++++++++++++++++++++++++++
drivers/misc/lkdtm/core.c | 3 ++
drivers/misc/lkdtm/lkdtm.h | 3 ++
3 files changed, 81 insertions(+)

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index de87693cf557..e4c61ffea35c 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/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)
{
/*
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index ee0d6e721441..2e04719b503c 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -129,6 +129,9 @@ 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),
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index c56d23e37643..8391081c6f13 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/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);
--
2.20.1
\
 
 \ /
  Last update: 2020-02-27 20:36    [W:0.053 / U:0.368 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site