The patch titled
Subject: kasan: test: bypass __alloc_size checks
has been added to the -mm tree. Its filename is
kasan-test-bypass-__alloc_size-checks.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-test-bypass-__alloc_size-checks.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-test-bypass-__alloc_size-checks.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: kasan: test: bypass __alloc_size checks
Intentional overflows, as performed by the KASAN tests, are detected at
compile time[1] (instead of only at run-time) with the addition of
__alloc_size. Fix this by forcing the compiler into not being able to
trust the size used following the kmalloc()s.
[1] https://lore.kernel.org/lkml/20211005184717.65c6d8eb39350395e387b71f@xxxxxxxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20211006181544.1670992-1-keescook@xxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/test_kasan.c | 8 +++++++-
lib/test_kasan_module.c | 2 ++
2 files changed, 9 insertions(+), 1 deletion(-)
--- a/lib/test_kasan.c~kasan-test-bypass-__alloc_size-checks
+++ a/lib/test_kasan.c
@@ -440,6 +440,7 @@ static void kmalloc_oob_memset_2(struct
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+ OPTIMIZER_HIDE_VAR(size);
KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 1, 0, 2));
kfree(ptr);
}
@@ -452,6 +453,7 @@ static void kmalloc_oob_memset_4(struct
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+ OPTIMIZER_HIDE_VAR(size);
KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 3, 0, 4));
kfree(ptr);
}
@@ -464,6 +466,7 @@ static void kmalloc_oob_memset_8(struct
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+ OPTIMIZER_HIDE_VAR(size);
KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 7, 0, 8));
kfree(ptr);
}
@@ -476,6 +479,7 @@ static void kmalloc_oob_memset_16(struct
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+ OPTIMIZER_HIDE_VAR(size);
KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 15, 0, 16));
kfree(ptr);
}
@@ -488,6 +492,7 @@ static void kmalloc_oob_in_memset(struct
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+ OPTIMIZER_HIDE_VAR(size);
KUNIT_EXPECT_KASAN_FAIL(test,
memset(ptr, 0, size + KASAN_GRANULE_SIZE));
kfree(ptr);
@@ -497,7 +502,7 @@ static void kmalloc_memmove_invalid_size
{
char *ptr;
size_t size = 64;
- volatile size_t invalid_size = -2;
+ size_t invalid_size = -2;
/*
* Hardware tag-based mode doesn't check memmove for negative size.
@@ -510,6 +515,7 @@ static void kmalloc_memmove_invalid_size
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
memset((char *)ptr, 0, 64);
+ OPTIMIZER_HIDE_VAR(invalid_size);
KUNIT_EXPECT_KASAN_FAIL(test,
memmove((char *)ptr, (char *)ptr + 4, invalid_size));
kfree(ptr);
--- a/lib/test_kasan_module.c~kasan-test-bypass-__alloc_size-checks
+++ a/lib/test_kasan_module.c
@@ -35,6 +35,8 @@ static noinline void __init copy_user_te
return;
}
+ OPTIMIZER_HIDE_VAR(size);
+
pr_info("out-of-bounds in copy_from_user()\n");
unused = copy_from_user(kmem, usermem, size + 1);
_
Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are
kasan-test-bypass-__alloc_size-checks.patch
rapidio-avoid-bogus-__alloc_size-warning.patch
compiler-attributes-add-__alloc_size-for-better-bounds-checking.patch
slab-clean-up-function-prototypes.patch
slab-add-__alloc_size-attributes-for-better-bounds-checking.patch
mm-kvmalloc-add-__alloc_size-attributes-for-better-bounds-checking.patch
mm-vmalloc-add-__alloc_size-attributes-for-better-bounds-checking.patch
mm-page_alloc-add-__alloc_size-attributes-for-better-bounds-checking.patch
percpu-add-__alloc_size-attributes-for-better-bounds-checking.patch
binfmt_elf-reintroduce-using-map_fixed_noreplace.patch
