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Message-ID: <20240812232910.2026387-4-mmaurer@google.com>
Date: Mon, 12 Aug 2024 23:29:03 +0000
From: Matthew Maurer <mmaurer@...gle.com>
To: dvyukov@...gle.com, ojeda@...nel.org,
Andrey Ryabinin <ryabinin.a.a@...il.com>, Andrew Morton <akpm@...ux-foundation.org>,
Alex Gaynor <alex.gaynor@...il.com>, Wedson Almeida Filho <wedsonaf@...il.com>
Cc: aliceryhl@...gle.com, samitolvanen@...gle.com,
Matthew Maurer <mmaurer@...gle.com>, Alexander Potapenko <glider@...gle.com>,
Andrey Konovalov <andreyknvl@...il.com>, Vincenzo Frascino <vincenzo.frascino@....com>,
Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
"Björn Roy Baron" <bjorn3_gh@...tonmail.com>, Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...sung.com>, linux-kernel@...r.kernel.org,
kasan-dev@...glegroups.com, linux-mm@...ck.org,
rust-for-linux@...r.kernel.org
Subject: [PATCH v2 3/3] kasan: rust: Add KASAN smoke test via UAF
Adds a smoke test to ensure that KASAN in Rust is actually detecting a
Rust-native UAF. There is significant room to expand this test suite,
but this will at least ensure that flags are having the intended effect.
Signed-off-by: Matthew Maurer <mmaurer@...gle.com>
---
mm/kasan/Makefile | 9 ++++++++-
mm/kasan/{kasan_test.c => kasan_test_c.c} | 13 +++++++++++++
mm/kasan/kasan_test_rust.rs | 17 +++++++++++++++++
3 files changed, 38 insertions(+), 1 deletion(-)
rename mm/kasan/{kasan_test.c => kasan_test_c.c} (99%)
create mode 100644 mm/kasan/kasan_test_rust.rs
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index 7634dd2a6128..d718b0f72009 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -44,7 +44,8 @@ ifndef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
CFLAGS_KASAN_TEST += -fno-builtin
endif
-CFLAGS_kasan_test.o := $(CFLAGS_KASAN_TEST)
+CFLAGS_kasan_test_c.o := $(CFLAGS_KASAN_TEST)
+RUSTFLAGS_kasan_test_rust.o := $(RUSTFLAGS_KASAN)
CFLAGS_kasan_test_module.o := $(CFLAGS_KASAN_TEST)
obj-y := common.o report.o
@@ -54,3 +55,9 @@ obj-$(CONFIG_KASAN_SW_TAGS) += init.o report_sw_tags.o shadow.o sw_tags.o tags.o
obj-$(CONFIG_KASAN_KUNIT_TEST) += kasan_test.o
obj-$(CONFIG_KASAN_MODULE_TEST) += kasan_test_module.o
+
+kasan_test-objs := kasan_test_c.o
+
+ifdef CONFIG_RUST
+kasan_test-objs += kasan_test_rust.o
+endif
diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test_c.c
similarity index 99%
rename from mm/kasan/kasan_test.c
rename to mm/kasan/kasan_test_c.c
index 7b32be2a3cf0..28821c90840e 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test_c.c
@@ -30,6 +30,7 @@
#include <asm/page.h>
#include "kasan.h"
+#include "kasan_test_rust.h"
#define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_GRANULE_SIZE)
@@ -1899,6 +1900,17 @@ static void match_all_mem_tag(struct kunit *test)
kfree(ptr);
}
+/*
+ * Check that Rust performing a uaf using `unsafe` is detected.
+ * This is an undirected smoke test to make sure that Rust is being sanitized
+ * appropriately.
+ */
+static void rust_uaf(struct kunit *test)
+{
+ KUNIT_EXPECT_KASAN_FAIL(test, kasan_test_rust_uaf());
+}
+
+
static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(kmalloc_oob_right),
KUNIT_CASE(kmalloc_oob_left),
@@ -1971,6 +1983,7 @@ static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(match_all_not_assigned),
KUNIT_CASE(match_all_ptr_tag),
KUNIT_CASE(match_all_mem_tag),
+ KUNIT_CASE(rust_uaf),
{}
};
diff --git a/mm/kasan/kasan_test_rust.rs b/mm/kasan/kasan_test_rust.rs
new file mode 100644
index 000000000000..6f4b43ea488c
--- /dev/null
+++ b/mm/kasan/kasan_test_rust.rs
@@ -0,0 +1,17 @@
+//! Helper crate for KASAN testing
+//! Provides behavior to check the sanitization of Rust code.
+use kernel::prelude::*;
+use core::ptr::addr_of_mut;
+
+/// Trivial UAF - allocate a big vector, grab a pointer partway through,
+/// drop the vector, and touch it.
+#[no_mangle]
+pub extern "C" fn kasan_test_rust_uaf() -> u8 {
+ let mut v: Vec<u8> = Vec::new();
+ for _ in 0..4096 {
+ v.push(0x42, GFP_KERNEL).unwrap();
+ }
+ let ptr: *mut u8 = addr_of_mut!(v[2048]);
+ drop(v);
+ unsafe { *ptr }
+}
--
2.46.0.76.ge559c4bf1a-goog
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