diff options
Diffstat (limited to 'drivers/misc/lkdtm/heap.c')
| -rw-r--r-- | drivers/misc/lkdtm/heap.c | 80 |
1 files changed, 65 insertions, 15 deletions
diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c index 62516078a619..c1a05b935894 100644 --- a/drivers/misc/lkdtm/heap.c +++ b/drivers/misc/lkdtm/heap.c @@ -4,6 +4,7 @@ * page allocation and slab allocations. */ #include "lkdtm.h" +#include <linux/kfence.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/sched.h> @@ -31,6 +32,7 @@ static void lkdtm_VMALLOC_LINEAR_OVERFLOW(void) char *one, *two; one = vzalloc(PAGE_SIZE); + OPTIMIZER_HIDE_VAR(one); two = vzalloc(PAGE_SIZE); pr_info("Attempting vmalloc linear overflow ...\n"); @@ -46,7 +48,7 @@ static void lkdtm_VMALLOC_LINEAR_OVERFLOW(void) * correctly. * * This should get caught by either memory tagging, KASan, or by using - * CONFIG_SLUB_DEBUG=y and slub_debug=ZF (or CONFIG_SLUB_DEBUG_ON=y). + * CONFIG_SLUB_DEBUG=y and slab_debug=ZF (or CONFIG_SLUB_DEBUG_ON=y). */ static void lkdtm_SLAB_LINEAR_OVERFLOW(void) { @@ -131,6 +133,64 @@ static void lkdtm_READ_AFTER_FREE(void) kfree(val); } +static void lkdtm_KFENCE_READ_AFTER_FREE(void) +{ + int *base, val, saw; + unsigned long timeout, resched_after; + size_t len = 1024; + /* + * The slub allocator will use the either the first word or + * the middle of the allocation to store the free pointer, + * depending on configurations. Store in the second word to + * avoid running into the freelist. + */ + size_t offset = sizeof(*base); + + /* + * 100x the sample interval should be more than enough to ensure we get + * a KFENCE allocation eventually. + */ + timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval); + /* + * Especially for non-preemption kernels, ensure the allocation-gate + * timer can catch up: after @resched_after, every failed allocation + * attempt yields, to ensure the allocation-gate timer is scheduled. + */ + resched_after = jiffies + msecs_to_jiffies(kfence_sample_interval); + do { + base = kmalloc(len, GFP_KERNEL); + if (!base) { + pr_err("FAIL: Unable to allocate kfence memory!\n"); + return; + } + + if (is_kfence_address(base)) { + val = 0x12345678; + base[offset] = val; + pr_info("Value in memory before free: %x\n", base[offset]); + + kfree(base); + + pr_info("Attempting bad read from freed memory\n"); + saw = base[offset]; + if (saw != val) { + /* Good! Poisoning happened, so declare a win. */ + pr_info("Memory correctly poisoned (%x)\n", saw); + } else { + pr_err("FAIL: Memory was not poisoned!\n"); + pr_expected_config_param(CONFIG_INIT_ON_FREE_DEFAULT_ON, "init_on_free"); + } + return; + } + + kfree(base); + if (time_after(jiffies, resched_after)) + cond_resched(); + } while (time_before(jiffies, timeout)); + + pr_err("FAIL: kfence memory never allocated!\n"); +} + static void lkdtm_WRITE_BUDDY_AFTER_FREE(void) { unsigned long p = __get_free_page(GFP_KERNEL); @@ -295,23 +355,12 @@ static void lkdtm_SLAB_FREE_PAGE(void) free_page(p); } -/* - * We have constructors to keep the caches distinctly separated without - * needing to boot with "slab_nomerge". - */ -static void ctor_double_free(void *region) -{ } -static void ctor_a(void *region) -{ } -static void ctor_b(void *region) -{ } - void __init lkdtm_heap_init(void) { double_free_cache = kmem_cache_create("lkdtm-heap-double_free", - 64, 0, 0, ctor_double_free); - a_cache = kmem_cache_create("lkdtm-heap-a", 64, 0, 0, ctor_a); - b_cache = kmem_cache_create("lkdtm-heap-b", 64, 0, 0, ctor_b); + 64, 0, SLAB_NO_MERGE, NULL); + a_cache = kmem_cache_create("lkdtm-heap-a", 64, 0, SLAB_NO_MERGE, NULL); + b_cache = kmem_cache_create("lkdtm-heap-b", 64, 0, SLAB_NO_MERGE, NULL); } void __exit lkdtm_heap_exit(void) @@ -326,6 +375,7 @@ static struct crashtype crashtypes[] = { CRASHTYPE(VMALLOC_LINEAR_OVERFLOW), CRASHTYPE(WRITE_AFTER_FREE), CRASHTYPE(READ_AFTER_FREE), + CRASHTYPE(KFENCE_READ_AFTER_FREE), CRASHTYPE(WRITE_BUDDY_AFTER_FREE), CRASHTYPE(READ_BUDDY_AFTER_FREE), CRASHTYPE(SLAB_INIT_ON_ALLOC), |