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lkdtm: Add tests for struct list corruption

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When building under CONFIG_DEBUG_LIST, list addition and removal will be
sanity-checked. This validates that the check is working as expected by
setting up classic corruption attacks against list manipulations, available
with the new lkdtm tests CORRUPT_LIST_ADD and CORRUPT_LIST_DEL.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
This commit is contained in:
Kees Cook 2016-08-17 14:42:12 -07:00 committed by Paul E. McKenney
parent de54ebbe26
commit 6819d101dd
3 changed files with 72 additions and 0 deletions
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2
drivers/misc/lkdtm.h
View File

@ -21,6 +21,8 @@ void lkdtm_SPINLOCKUP(void);
void lkdtm_HUNG_TASK(void); void lkdtm_HUNG_TASK(void);
void lkdtm_ATOMIC_UNDERFLOW(void); void lkdtm_ATOMIC_UNDERFLOW(void);
void lkdtm_ATOMIC_OVERFLOW(void); void lkdtm_ATOMIC_OVERFLOW(void);
void lkdtm_CORRUPT_LIST_ADD(void);
void lkdtm_CORRUPT_LIST_DEL(void);
/* lkdtm_heap.c */ /* lkdtm_heap.c */
void lkdtm_OVERWRITE_ALLOCATION(void); void lkdtm_OVERWRITE_ALLOCATION(void);

68
drivers/misc/lkdtm_bugs.c
View File

@ -5,8 +5,13 @@
* test source files. * test source files.
*/ */
#include "lkdtm.h" #include "lkdtm.h"
#include <linux/list.h>
#include <linux/sched.h> #include <linux/sched.h>
struct lkdtm_list {
struct list_head node;
};
/* /*
* Make sure our attempts to over run the kernel stack doesn't trigger * Make sure our attempts to over run the kernel stack doesn't trigger
* a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
@ -146,3 +151,66 @@ void lkdtm_ATOMIC_OVERFLOW(void)
pr_info("attempting bad atomic overflow\n"); pr_info("attempting bad atomic overflow\n");
atomic_inc(&over); atomic_inc(&over);
} }
void lkdtm_CORRUPT_LIST_ADD(void)
{
/*
* Initially, an empty list via LIST_HEAD:
* test_head.next = &test_head
* test_head.prev = &test_head
*/
LIST_HEAD(test_head);
struct lkdtm_list good, bad;
void *target[2] = { };
void *redirection = &target;
pr_info("attempting good list addition\n");
/*
* Adding to the list performs these actions:
* test_head.next->prev = &good.node
* good.node.next = test_head.next
* good.node.prev = test_head
* test_head.next = good.node
*/
list_add(&good.node, &test_head);
pr_info("attempting corrupted list addition\n");
/*
* In simulating this "write what where" primitive, the "what" is
* the address of &bad.node, and the "where" is the address held
* by "redirection".
*/
test_head.next = redirection;
list_add(&bad.node, &test_head);
if (target[0] == NULL && target[1] == NULL)
pr_err("Overwrite did not happen, but no BUG?!\n");
else
pr_err("list_add() corruption not detected!\n");
}
void lkdtm_CORRUPT_LIST_DEL(void)
{
LIST_HEAD(test_head);
struct lkdtm_list item;
void *target[2] = { };
void *redirection = &target;
list_add(&item.node, &test_head);
pr_info("attempting good list removal\n");
list_del(&item.node);
pr_info("attempting corrupted list removal\n");
list_add(&item.node, &test_head);
/* As with the list_add() test above, this corrupts "next". */
item.node.next = redirection;
list_del(&item.node);
if (target[0] == NULL && target[1] == NULL)
pr_err("Overwrite did not happen, but no BUG?!\n");
else
pr_err("list_del() corruption not detected!\n");
}

2
drivers/misc/lkdtm_core.c
View File

@ -197,6 +197,8 @@ struct crashtype crashtypes[] = {
CRASHTYPE(EXCEPTION), CRASHTYPE(EXCEPTION),
CRASHTYPE(LOOP), CRASHTYPE(LOOP),
CRASHTYPE(OVERFLOW), CRASHTYPE(OVERFLOW),
CRASHTYPE(CORRUPT_LIST_ADD),
CRASHTYPE(CORRUPT_LIST_DEL),
CRASHTYPE(CORRUPT_STACK), CRASHTYPE(CORRUPT_STACK),
CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE), CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
CRASHTYPE(OVERWRITE_ALLOCATION), CRASHTYPE(OVERWRITE_ALLOCATION),