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Date: Thu, 13 Aug 2020 18:19:22 +0300
From: Alexander Popov <alex.popov@...ux.com>
To: Kees Cook <keescook@...omium.org>,
Jann Horn <jannh@...gle.com>,
Will Deacon <will@...nel.org>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Alexander Potapenko <glider@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Masahiro Yamada <masahiroy@...nel.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Peter Zijlstra <peterz@...radead.org>,
Krzysztof Kozlowski <krzk@...nel.org>,
Patrick Bellasi <patrick.bellasi@....com>,
David Howells <dhowells@...hat.com>,
Eric Biederman <ebiederm@...ssion.com>,
Johannes Weiner <hannes@...xchg.org>,
Laura Abbott <labbott@...hat.com>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
kasan-dev@...glegroups.com,
linux-mm@...ck.org,
kernel-hardening@...ts.openwall.com,
linux-kernel@...r.kernel.org,
Alexander Popov <alex.popov@...ux.com>
Cc: notify@...nel.org
Subject: [PATCH RFC 2/2] lkdtm: Add heap spraying test
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 <alex.popov@...ux.com>
---
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
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