Add a simple test for CONFIG_SLAB_QUARANTINE. It performs heap spraying that aims to reallocate the recently freed heap object. This technique is used for exploiting use-after-free vulnerabilities in the kernel code.
This test shows that CONFIG_SLAB_QUARANTINE breaks heap spraying exploitation technique. Signed-off-by: Alexander Popov <[email protected]> --- drivers/misc/lkdtm/core.c | 1 + drivers/misc/lkdtm/heap.c | 40 ++++++++++++++++++++++++++++++++++++++ drivers/misc/lkdtm/lkdtm.h | 1 + 3 files changed, 42 insertions(+) diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c index a5e344df9166..78b7669c35eb 100644 --- a/drivers/misc/lkdtm/core.c +++ b/drivers/misc/lkdtm/core.c @@ -126,6 +126,7 @@ static const struct crashtype crashtypes[] = { CRASHTYPE(SLAB_FREE_DOUBLE), CRASHTYPE(SLAB_FREE_CROSS), CRASHTYPE(SLAB_FREE_PAGE), + CRASHTYPE(HEAP_SPRAY), CRASHTYPE(SOFTLOCKUP), CRASHTYPE(HARDLOCKUP), CRASHTYPE(SPINLOCKUP), diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c index 1323bc16f113..a72a241e314a 100644 --- a/drivers/misc/lkdtm/heap.c +++ b/drivers/misc/lkdtm/heap.c @@ -205,6 +205,46 @@ static void ctor_a(void *region) static void ctor_b(void *region) { } +#define HEAP_SPRAY_SIZE 128 + +void lkdtm_HEAP_SPRAY(void) +{ + int *addr; + int *spray_addrs[HEAP_SPRAY_SIZE] = { 0 }; + unsigned long i = 0; + + addr = kmem_cache_alloc(a_cache, GFP_KERNEL); + if (!addr) { + pr_info("Unable to allocate memory in lkdtm-heap-a cache\n"); + return; + } + + *addr = 0x31337; + kmem_cache_free(a_cache, addr); + + pr_info("Performing heap spraying...\n"); + for (i = 0; i < HEAP_SPRAY_SIZE; i++) { + spray_addrs[i] = kmem_cache_alloc(a_cache, GFP_KERNEL); + *spray_addrs[i] = 0x31337; + pr_info("attempt %lu: spray alloc addr %p vs freed addr %p\n", + i, spray_addrs[i], addr); + if (spray_addrs[i] == addr) { + pr_info("freed addr is reallocated!\n"); + break; + } + } + + if (i < HEAP_SPRAY_SIZE) + pr_info("FAIL! Heap spraying succeed :(\n"); + else + pr_info("OK! Heap spraying hasn't succeed :)\n"); + + for (i = 0; i < HEAP_SPRAY_SIZE; i++) { + if (spray_addrs[i]) + kmem_cache_free(a_cache, spray_addrs[i]); + } +} + void __init lkdtm_heap_init(void) { double_free_cache = kmem_cache_create("lkdtm-heap-double_free", diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h index 8878538b2c13..dfafb4ae6f3a 100644 --- a/drivers/misc/lkdtm/lkdtm.h +++ b/drivers/misc/lkdtm/lkdtm.h @@ -45,6 +45,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void); void lkdtm_SLAB_FREE_DOUBLE(void); void lkdtm_SLAB_FREE_CROSS(void); void lkdtm_SLAB_FREE_PAGE(void); +void lkdtm_HEAP_SPRAY(void); /* lkdtm_perms.c */ void __init lkdtm_perms_init(void); -- 2.26.2
