From 9c4f6ebc3665b33f15ee97ba1eb2c9bed341b8e6 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 23 Jun 2021 13:39:32 -0700 Subject: [PATCH] lkdtm/heap: Add vmalloc linear overflow test Similar to the existing slab overflow and stack exhaustion tests, add VMALLOC_LINEAR_OVERFLOW (and rename the slab test SLAB_LINEAR_OVERFLOW). Additionally unmarks the test as destructive. (It should be safe in the face of misbehavior.) Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210623203936.3151093-6-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman --- drivers/misc/lkdtm/core.c | 3 ++- drivers/misc/lkdtm/heap.c | 22 +++++++++++++++++++++- drivers/misc/lkdtm/lkdtm.h | 3 ++- tools/testing/selftests/lkdtm/tests.txt | 3 ++- 4 files changed, 27 insertions(+), 4 deletions(-) diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c index 8024b6a5cc7f..645b31e98c77 100644 --- a/drivers/misc/lkdtm/core.c +++ b/drivers/misc/lkdtm/core.c @@ -120,7 +120,8 @@ static const struct crashtype crashtypes[] = { CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE), CRASHTYPE(FORTIFY_OBJECT), CRASHTYPE(FORTIFY_SUBOBJECT), - CRASHTYPE(OVERWRITE_ALLOCATION), + CRASHTYPE(SLAB_LINEAR_OVERFLOW), + CRASHTYPE(VMALLOC_LINEAR_OVERFLOW), CRASHTYPE(WRITE_AFTER_FREE), CRASHTYPE(READ_AFTER_FREE), CRASHTYPE(WRITE_BUDDY_AFTER_FREE), diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c index 1323bc16f113..36be5e353cd0 100644 --- a/drivers/misc/lkdtm/heap.c +++ b/drivers/misc/lkdtm/heap.c @@ -5,24 +5,44 @@ */ #include "lkdtm.h" #include +#include #include static struct kmem_cache *double_free_cache; static struct kmem_cache *a_cache; static struct kmem_cache *b_cache; +/* + * If there aren't guard pages, it's likely that a consecutive allocation will + * let us overflow into the second allocation without overwriting something real. + */ +void lkdtm_VMALLOC_LINEAR_OVERFLOW(void) +{ + char *one, *two; + + one = vzalloc(PAGE_SIZE); + two = vzalloc(PAGE_SIZE); + + pr_info("Attempting vmalloc linear overflow ...\n"); + memset(one, 0xAA, PAGE_SIZE + 1); + + vfree(two); + vfree(one); +} + /* * This tries to stay within the next largest power-of-2 kmalloc cache * to avoid actually overwriting anything important if it's not detected * correctly. */ -void lkdtm_OVERWRITE_ALLOCATION(void) +void lkdtm_SLAB_LINEAR_OVERFLOW(void) { size_t len = 1020; u32 *data = kmalloc(len, GFP_KERNEL); if (!data) return; + pr_info("Attempting slab linear overflow ...\n"); data[1024 / sizeof(u32)] = 0x12345678; kfree(data); } diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h index 99f90d3e5e9c..c6baf4f1e1db 100644 --- a/drivers/misc/lkdtm/lkdtm.h +++ b/drivers/misc/lkdtm/lkdtm.h @@ -39,7 +39,8 @@ void lkdtm_FORTIFY_SUBOBJECT(void); /* heap.c */ void __init lkdtm_heap_init(void); void __exit lkdtm_heap_exit(void); -void lkdtm_OVERWRITE_ALLOCATION(void); +void lkdtm_VMALLOC_LINEAR_OVERFLOW(void); +void lkdtm_SLAB_LINEAR_OVERFLOW(void); void lkdtm_WRITE_AFTER_FREE(void); void lkdtm_READ_AFTER_FREE(void); void lkdtm_WRITE_BUDDY_AFTER_FREE(void); diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt index a94d4d8eeb5c..30080cc15623 100644 --- a/tools/testing/selftests/lkdtm/tests.txt +++ b/tools/testing/selftests/lkdtm/tests.txt @@ -15,7 +15,8 @@ UNSET_SMEP pinned CR4 bits changed: DOUBLE_FAULT CORRUPT_PAC UNALIGNED_LOAD_STORE_WRITE -#OVERWRITE_ALLOCATION Corrupts memory on failure +SLAB_LINEAR_OVERFLOW +VMALLOC_LINEAR_OVERFLOW #WRITE_AFTER_FREE Corrupts memory on failure READ_AFTER_FREE call trace:|Memory correctly poisoned #WRITE_BUDDY_AFTER_FREE Corrupts memory on failure -- 2.20.1