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authorLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 10:21:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 10:21:20 -0700
commit29c8c18363eee546d19bd95daa1e33c64ee74414 (patch)
tree39245c8e255f1bd8547c964cb886f7699dd986e1 /lib
parentaa5b537b0ecc16992577b013f11112d54c7ce869 (diff)
parent25fd2d41b505d0640bdfe67aa77c549de2d3c18a (diff)
downloadlinux-29c8c18363eee546d19bd95daa1e33c64ee74414.tar.bz2
Merge branch 'akpm' (patches from Andrew)
Merge yet more updates from Andrew Morton: "This is the material which was staged after willystuff in linux-next. Subsystems affected by this patch series: mm (debug, selftests, pagecache, thp, rmap, migration, kasan, hugetlb, pagemap, madvise), and selftests" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (113 commits) selftests: kselftest framework: provide "finished" helper mm: madvise: MADV_DONTNEED_LOCKED mm: fix race between MADV_FREE reclaim and blkdev direct IO read mm: generalize ARCH_HAS_FILTER_PGPROT mm: unmap_mapping_range_tree() with i_mmap_rwsem shared mm: warn on deleting redirtied only if accounted mm/huge_memory: remove stale locking logic from __split_huge_pmd() mm/huge_memory: remove stale page_trans_huge_mapcount() mm/swapfile: remove stale reuse_swap_page() mm/khugepaged: remove reuse_swap_page() usage mm/huge_memory: streamline COW logic in do_huge_pmd_wp_page() mm: streamline COW logic in do_swap_page() mm: slightly clarify KSM logic in do_swap_page() mm: optimize do_wp_page() for fresh pages in local LRU pagevecs mm: optimize do_wp_page() for exclusive pages in the swapcache mm/huge_memory: make is_transparent_hugepage() static userfaultfd/selftests: enable hugetlb remap and remove event testing selftests/vm: add hugetlb madvise MADV_DONTNEED MADV_REMOVE test mm: enable MADV_DONTNEED for hugetlb mappings kasan: disable LOCKDEP when printing reports ...
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.kasan20
-rw-r--r--lib/test_kasan.c239
-rw-r--r--lib/vsprintf.c8
3 files changed, 228 insertions, 39 deletions
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 879757b6dd14..1f3e620188a2 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -178,17 +178,17 @@ config KASAN_TAGS_IDENTIFY
memory consumption.
config KASAN_VMALLOC
- bool "Back mappings in vmalloc space with real shadow memory"
- depends on KASAN_GENERIC && HAVE_ARCH_KASAN_VMALLOC
+ bool "Check accesses to vmalloc allocations"
+ depends on HAVE_ARCH_KASAN_VMALLOC
help
- By default, the shadow region for vmalloc space is the read-only
- zero page. This means that KASAN cannot detect errors involving
- vmalloc space.
-
- Enabling this option will hook in to vmap/vmalloc and back those
- mappings with real shadow memory allocated on demand. This allows
- for KASAN to detect more sorts of errors (and to support vmapped
- stacks), but at the cost of higher memory usage.
+ This mode makes KASAN check accesses to vmalloc allocations for
+ validity.
+
+ With software KASAN modes, checking is done for all types of vmalloc
+ allocations. Enabling this option leads to higher memory usage.
+
+ With hardware tag-based KASAN, only VM_ALLOC mappings are checked.
+ There is no additional memory usage.
config KASAN_KUNIT_TEST
tristate "KUnit-compatible tests of KASAN bug detection capabilities" if !KUNIT_ALL_TESTS
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 3b413f8c8a71..ad880231dfa8 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -19,6 +19,7 @@
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/vmalloc.h>
+#include <linux/set_memory.h>
#include <asm/page.h>
@@ -36,7 +37,7 @@ void *kasan_ptr_result;
int kasan_int_result;
static struct kunit_resource resource;
-static struct kunit_kasan_expectation fail_data;
+static struct kunit_kasan_status test_status;
static bool multishot;
/*
@@ -53,58 +54,63 @@ static int kasan_test_init(struct kunit *test)
}
multishot = kasan_save_enable_multi_shot();
- fail_data.report_found = false;
+ test_status.report_found = false;
+ test_status.sync_fault = false;
kunit_add_named_resource(test, NULL, NULL, &resource,
- "kasan_data", &fail_data);
+ "kasan_status", &test_status);
return 0;
}
static void kasan_test_exit(struct kunit *test)
{
kasan_restore_multi_shot(multishot);
- KUNIT_EXPECT_FALSE(test, fail_data.report_found);
+ KUNIT_EXPECT_FALSE(test, test_status.report_found);
}
/**
* KUNIT_EXPECT_KASAN_FAIL() - check that the executed expression produces a
* KASAN report; causes a test failure otherwise. This relies on a KUnit
- * resource named "kasan_data". Do not use this name for KUnit resources
+ * resource named "kasan_status". Do not use this name for KUnit resources
* outside of KASAN tests.
*
- * For hardware tag-based KASAN in sync mode, when a tag fault happens, tag
+ * For hardware tag-based KASAN, when a synchronous tag fault happens, tag
* checking is auto-disabled. When this happens, this test handler reenables
* tag checking. As tag checking can be only disabled or enabled per CPU,
* this handler disables migration (preemption).
*
- * Since the compiler doesn't see that the expression can change the fail_data
+ * Since the compiler doesn't see that the expression can change the test_status
* fields, it can reorder or optimize away the accesses to those fields.
* Use READ/WRITE_ONCE() for the accesses and compiler barriers around the
* expression to prevent that.
*
- * In between KUNIT_EXPECT_KASAN_FAIL checks, fail_data.report_found is kept as
- * false. This allows detecting KASAN reports that happen outside of the checks
- * by asserting !fail_data.report_found at the start of KUNIT_EXPECT_KASAN_FAIL
- * and in kasan_test_exit.
+ * In between KUNIT_EXPECT_KASAN_FAIL checks, test_status.report_found is kept
+ * as false. This allows detecting KASAN reports that happen outside of the
+ * checks by asserting !test_status.report_found at the start of
+ * KUNIT_EXPECT_KASAN_FAIL and in kasan_test_exit.
*/
#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \
kasan_sync_fault_possible()) \
migrate_disable(); \
- KUNIT_EXPECT_FALSE(test, READ_ONCE(fail_data.report_found)); \
+ KUNIT_EXPECT_FALSE(test, READ_ONCE(test_status.report_found)); \
barrier(); \
expression; \
barrier(); \
- if (!READ_ONCE(fail_data.report_found)) { \
+ if (kasan_async_fault_possible()) \
+ kasan_force_async_fault(); \
+ if (!READ_ONCE(test_status.report_found)) { \
KUNIT_FAIL(test, KUNIT_SUBTEST_INDENT "KASAN failure " \
"expected in \"" #expression \
"\", but none occurred"); \
} \
- if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \
- if (READ_ONCE(fail_data.report_found)) \
- kasan_enable_tagging_sync(); \
+ if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \
+ kasan_sync_fault_possible()) { \
+ if (READ_ONCE(test_status.report_found) && \
+ READ_ONCE(test_status.sync_fault)) \
+ kasan_enable_tagging(); \
migrate_enable(); \
} \
- WRITE_ONCE(fail_data.report_found, false); \
+ WRITE_ONCE(test_status.report_found, false); \
} while (0)
#define KASAN_TEST_NEEDS_CONFIG_ON(test, config) do { \
@@ -780,7 +786,7 @@ static void ksize_uaf(struct kunit *test)
static void kasan_stack_oob(struct kunit *test)
{
char stack_array[10];
- /* See comment in kasan_global_oob. */
+ /* See comment in kasan_global_oob_right. */
char *volatile array = stack_array;
char *p = &array[ARRAY_SIZE(stack_array) + OOB_TAG_OFF];
@@ -793,7 +799,7 @@ static void kasan_alloca_oob_left(struct kunit *test)
{
volatile int i = 10;
char alloca_array[i];
- /* See comment in kasan_global_oob. */
+ /* See comment in kasan_global_oob_right. */
char *volatile array = alloca_array;
char *p = array - 1;
@@ -808,7 +814,7 @@ static void kasan_alloca_oob_right(struct kunit *test)
{
volatile int i = 10;
char alloca_array[i];
- /* See comment in kasan_global_oob. */
+ /* See comment in kasan_global_oob_right. */
char *volatile array = alloca_array;
char *p = array + i;
@@ -1057,21 +1063,186 @@ static void kmalloc_double_kzfree(struct kunit *test)
KUNIT_EXPECT_KASAN_FAIL(test, kfree_sensitive(ptr));
}
+static void vmalloc_helpers_tags(struct kunit *test)
+{
+ void *ptr;
+
+ /* This test is intended for tag-based modes. */
+ KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC);
+
+ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC);
+
+ ptr = vmalloc(PAGE_SIZE);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+
+ /* Check that the returned pointer is tagged. */
+ KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN);
+ KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL);
+
+ /* Make sure exported vmalloc helpers handle tagged pointers. */
+ KUNIT_ASSERT_TRUE(test, is_vmalloc_addr(ptr));
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, vmalloc_to_page(ptr));
+
+#if !IS_MODULE(CONFIG_KASAN_KUNIT_TEST)
+ {
+ int rv;
+
+ /* Make sure vmalloc'ed memory permissions can be changed. */
+ rv = set_memory_ro((unsigned long)ptr, 1);
+ KUNIT_ASSERT_GE(test, rv, 0);
+ rv = set_memory_rw((unsigned long)ptr, 1);
+ KUNIT_ASSERT_GE(test, rv, 0);
+ }
+#endif
+
+ vfree(ptr);
+}
+
static void vmalloc_oob(struct kunit *test)
{
- void *area;
+ char *v_ptr, *p_ptr;
+ struct page *page;
+ size_t size = PAGE_SIZE / 2 - KASAN_GRANULE_SIZE - 5;
KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC);
+ v_ptr = vmalloc(size);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_ptr);
+
+ OPTIMIZER_HIDE_VAR(v_ptr);
+
/*
- * We have to be careful not to hit the guard page.
+ * We have to be careful not to hit the guard page in vmalloc tests.
* The MMU will catch that and crash us.
*/
- area = vmalloc(3000);
- KUNIT_ASSERT_NOT_ERR_OR_NULL(test, area);
- KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)area)[3100]);
- vfree(area);
+ /* Make sure in-bounds accesses are valid. */
+ v_ptr[0] = 0;
+ v_ptr[size - 1] = 0;
+
+ /*
+ * An unaligned access past the requested vmalloc size.
+ * Only generic KASAN can precisely detect these.
+ */
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+ KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)v_ptr)[size]);
+
+ /* An aligned access into the first out-of-bounds granule. */
+ KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)v_ptr)[size + 5]);
+
+ /* Check that in-bounds accesses to the physical page are valid. */
+ page = vmalloc_to_page(v_ptr);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, page);
+ p_ptr = page_address(page);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_ptr);
+ p_ptr[0] = 0;
+
+ vfree(v_ptr);
+
+ /*
+ * We can't check for use-after-unmap bugs in this nor in the following
+ * vmalloc tests, as the page might be fully unmapped and accessing it
+ * will crash the kernel.
+ */
+}
+
+static void vmap_tags(struct kunit *test)
+{
+ char *p_ptr, *v_ptr;
+ struct page *p_page, *v_page;
+
+ /*
+ * This test is specifically crafted for the software tag-based mode,
+ * the only tag-based mode that poisons vmap mappings.
+ */
+ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_SW_TAGS);
+
+ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC);
+
+ p_page = alloc_pages(GFP_KERNEL, 1);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_page);
+ p_ptr = page_address(p_page);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_ptr);
+
+ v_ptr = vmap(&p_page, 1, VM_MAP, PAGE_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_ptr);
+
+ /*
+ * We can't check for out-of-bounds bugs in this nor in the following
+ * vmalloc tests, as allocations have page granularity and accessing
+ * the guard page will crash the kernel.
+ */
+
+ KUNIT_EXPECT_GE(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_MIN);
+ KUNIT_EXPECT_LT(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_KERNEL);
+
+ /* Make sure that in-bounds accesses through both pointers work. */
+ *p_ptr = 0;
+ *v_ptr = 0;
+
+ /* Make sure vmalloc_to_page() correctly recovers the page pointer. */
+ v_page = vmalloc_to_page(v_ptr);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_page);
+ KUNIT_EXPECT_PTR_EQ(test, p_page, v_page);
+
+ vunmap(v_ptr);
+ free_pages((unsigned long)p_ptr, 1);
+}
+
+static void vm_map_ram_tags(struct kunit *test)
+{
+ char *p_ptr, *v_ptr;
+ struct page *page;
+
+ /*
+ * This test is specifically crafted for the software tag-based mode,
+ * the only tag-based mode that poisons vm_map_ram mappings.
+ */
+ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_SW_TAGS);
+
+ page = alloc_pages(GFP_KERNEL, 1);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, page);
+ p_ptr = page_address(page);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_ptr);
+
+ v_ptr = vm_map_ram(&page, 1, -1);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_ptr);
+
+ KUNIT_EXPECT_GE(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_MIN);
+ KUNIT_EXPECT_LT(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_KERNEL);
+
+ /* Make sure that in-bounds accesses through both pointers work. */
+ *p_ptr = 0;
+ *v_ptr = 0;
+
+ vm_unmap_ram(v_ptr, 1);
+ free_pages((unsigned long)p_ptr, 1);
+}
+
+static void vmalloc_percpu(struct kunit *test)
+{
+ char __percpu *ptr;
+ int cpu;
+
+ /*
+ * This test is specifically crafted for the software tag-based mode,
+ * the only tag-based mode that poisons percpu mappings.
+ */
+ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_SW_TAGS);
+
+ ptr = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
+
+ for_each_possible_cpu(cpu) {
+ char *c_ptr = per_cpu_ptr(ptr, cpu);
+
+ KUNIT_EXPECT_GE(test, (u8)get_tag(c_ptr), (u8)KASAN_TAG_MIN);
+ KUNIT_EXPECT_LT(test, (u8)get_tag(c_ptr), (u8)KASAN_TAG_KERNEL);
+
+ /* Make sure that in-bounds accesses don't crash the kernel. */
+ *c_ptr = 0;
+ }
+
+ free_percpu(ptr);
}
/*
@@ -1105,6 +1276,18 @@ static void match_all_not_assigned(struct kunit *test)
KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL);
free_pages((unsigned long)ptr, order);
}
+
+ if (!IS_ENABLED(CONFIG_KASAN_VMALLOC))
+ return;
+
+ for (i = 0; i < 256; i++) {
+ size = (get_random_int() % 1024) + 1;
+ ptr = vmalloc(size);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+ KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN);
+ KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL);
+ vfree(ptr);
+ }
}
/* Check that 0xff works as a match-all pointer tag for tag-based modes. */
@@ -1210,7 +1393,11 @@ static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(kasan_bitops_generic),
KUNIT_CASE(kasan_bitops_tags),
KUNIT_CASE(kmalloc_double_kzfree),
+ KUNIT_CASE(vmalloc_helpers_tags),
KUNIT_CASE(vmalloc_oob),
+ KUNIT_CASE(vmap_tags),
+ KUNIT_CASE(vm_map_ram_tags),
+ KUNIT_CASE(vmalloc_percpu),
KUNIT_CASE(match_all_not_assigned),
KUNIT_CASE(match_all_ptr_tag),
KUNIT_CASE(match_all_mem_tag),
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 53fe73a48adf..40d26a07a133 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2906,13 +2906,15 @@ int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
int i;
+ if (unlikely(!size))
+ return 0;
+
i = vsnprintf(buf, size, fmt, args);
if (likely(i < size))
return i;
- if (size != 0)
- return size - 1;
- return 0;
+
+ return size - 1;
}
EXPORT_SYMBOL(vscnprintf);