Commit b1d57289 authored by Dmitry Vyukov's avatar Dmitry Vyukov Committed by Linus Torvalds

kasan: detect invalid frees

Detect frees of pointers into middle of heap objects.

Link: http://lkml.kernel.org/r/cb569193190356beb018a03bb8d6fbae67e7adbc.1514378558.git.dvyukov@google.comSigned-off-by: default avatarDmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1db0e0f9
......@@ -523,6 +523,54 @@ static noinline void __init kasan_alloca_oob_right(void)
*(volatile char *)p;
}
static noinline void __init kmem_cache_double_free(void)
{
char *p;
size_t size = 200;
struct kmem_cache *cache;
cache = kmem_cache_create("test_cache", size, 0, 0, NULL);
if (!cache) {
pr_err("Cache allocation failed\n");
return;
}
pr_info("double-free on heap object\n");
p = kmem_cache_alloc(cache, GFP_KERNEL);
if (!p) {
pr_err("Allocation failed\n");
kmem_cache_destroy(cache);
return;
}
kmem_cache_free(cache, p);
kmem_cache_free(cache, p);
kmem_cache_destroy(cache);
}
static noinline void __init kmem_cache_invalid_free(void)
{
char *p;
size_t size = 200;
struct kmem_cache *cache;
cache = kmem_cache_create("test_cache", size, 0, SLAB_TYPESAFE_BY_RCU,
NULL);
if (!cache) {
pr_err("Cache allocation failed\n");
return;
}
pr_info("invalid-free of heap object\n");
p = kmem_cache_alloc(cache, GFP_KERNEL);
if (!p) {
pr_err("Allocation failed\n");
kmem_cache_destroy(cache);
return;
}
kmem_cache_free(cache, p + 1);
kmem_cache_destroy(cache);
}
static int __init kmalloc_tests_init(void)
{
/*
......@@ -560,6 +608,8 @@ static int __init kmalloc_tests_init(void)
ksize_unpoisons_memory();
copy_user_test();
use_after_scope_test();
kmem_cache_double_free();
kmem_cache_invalid_free();
kasan_restore_multi_shot(multishot);
......
......@@ -495,6 +495,12 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
s8 shadow_byte;
unsigned long rounded_up_size;
if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
object)) {
kasan_report_invalid_free(object, ip);
return true;
}
/* RCU slabs could be legally used after free within the RCU period */
if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
return false;
......
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