diff options
Diffstat (limited to 'drivers/misc/lkdtm_bugs.c')
| -rw-r--r-- | drivers/misc/lkdtm_bugs.c | 163 |
1 files changed, 148 insertions, 15 deletions
diff --git a/drivers/misc/lkdtm_bugs.c b/drivers/misc/lkdtm_bugs.c index 182ae1894b32..e3f4cd8876b5 100644 --- a/drivers/misc/lkdtm_bugs.c +++ b/drivers/misc/lkdtm_bugs.c @@ -5,8 +5,14 @@ * test source files. */ #include "lkdtm.h" +#include <linux/list.h> +#include <linux/refcount.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 * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we @@ -75,12 +81,18 @@ void lkdtm_OVERFLOW(void) (void) recursive_loop(recur_count); } +static noinline void __lkdtm_CORRUPT_STACK(void *stack) +{ + memset(stack, 'a', 64); +} + noinline void lkdtm_CORRUPT_STACK(void) { /* Use default char array length that triggers stack protection. */ char data[8]; + __lkdtm_CORRUPT_STACK(&data); - memset((void *)data, 0, 64); + pr_info("Corrupted stack with '%16s'...\n", data); } void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void) @@ -123,26 +135,147 @@ void lkdtm_HUNG_TASK(void) schedule(); } -void lkdtm_ATOMIC_UNDERFLOW(void) +void lkdtm_REFCOUNT_SATURATE_INC(void) { - atomic_t under = ATOMIC_INIT(INT_MIN); + refcount_t over = REFCOUNT_INIT(UINT_MAX - 1); + + pr_info("attempting good refcount decrement\n"); + refcount_dec(&over); + refcount_inc(&over); + + pr_info("attempting bad refcount inc overflow\n"); + refcount_inc(&over); + refcount_inc(&over); + if (refcount_read(&over) == UINT_MAX) + pr_err("Correctly stayed saturated, but no BUG?!\n"); + else + pr_err("Fail: refcount wrapped\n"); +} + +void lkdtm_REFCOUNT_SATURATE_ADD(void) +{ + refcount_t over = REFCOUNT_INIT(UINT_MAX - 1); + + pr_info("attempting good refcount decrement\n"); + refcount_dec(&over); + refcount_inc(&over); - pr_info("attempting good atomic increment\n"); - atomic_inc(&under); - atomic_dec(&under); + pr_info("attempting bad refcount add overflow\n"); + refcount_add(2, &over); + if (refcount_read(&over) == UINT_MAX) + pr_err("Correctly stayed saturated, but no BUG?!\n"); + else + pr_err("Fail: refcount wrapped\n"); +} + +void lkdtm_REFCOUNT_ZERO_DEC(void) +{ + refcount_t zero = REFCOUNT_INIT(1); - pr_info("attempting bad atomic underflow\n"); - atomic_dec(&under); + pr_info("attempting bad refcount decrement to zero\n"); + refcount_dec(&zero); + if (refcount_read(&zero) == 0) + pr_err("Stayed at zero, but no BUG?!\n"); + else + pr_err("Fail: refcount went crazy\n"); } -void lkdtm_ATOMIC_OVERFLOW(void) +void lkdtm_REFCOUNT_ZERO_SUB(void) { - atomic_t over = ATOMIC_INIT(INT_MAX); + refcount_t zero = REFCOUNT_INIT(1); - pr_info("attempting good atomic decrement\n"); - atomic_dec(&over); - atomic_inc(&over); + pr_info("attempting bad refcount subtract past zero\n"); + if (!refcount_sub_and_test(2, &zero)) + pr_info("wrap attempt was noticed\n"); + if (refcount_read(&zero) == 1) + pr_err("Correctly stayed above 0, but no BUG?!\n"); + else + pr_err("Fail: refcount wrapped\n"); +} + +void lkdtm_REFCOUNT_ZERO_INC(void) +{ + refcount_t zero = REFCOUNT_INIT(0); - pr_info("attempting bad atomic overflow\n"); - atomic_inc(&over); + pr_info("attempting bad refcount increment from zero\n"); + refcount_inc(&zero); + if (refcount_read(&zero) == 0) + pr_err("Stayed at zero, but no BUG?!\n"); + else + pr_err("Fail: refcount went past zero\n"); +} + +void lkdtm_REFCOUNT_ZERO_ADD(void) +{ + refcount_t zero = REFCOUNT_INIT(0); + + pr_info("attempting bad refcount addition from zero\n"); + refcount_add(2, &zero); + if (refcount_read(&zero) == 0) + pr_err("Stayed at zero, but no BUG?!\n"); + else + pr_err("Fail: refcount went past zero\n"); +} + +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 = ⌖ + + 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 = ⌖ + + 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"); } |