summaryrefslogtreecommitdiff
path: root/lib
diff options
context:
space:
mode:
authorAndrey Konovalov <andreyknvl@google.com>2021-02-26 04:20:19 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-26 20:41:03 +0300
commit26a5ca7a73be31f76c291465680517cde37051ca (patch)
tree70c65d14632e95c58ef2812bc3575a55327265cb /lib
parentb87c28b9a7ef64590943435ea59f40092f2376d5 (diff)
downloadlinux-26a5ca7a73be31f76c291465680517cde37051ca.tar.xz
kasan, mm: fail krealloc on freed objects
Currently, if krealloc() is called on a freed object with KASAN enabled, it allocates and returns a new object, but doesn't copy any memory from the old one as ksize() returns 0. This makes the caller believe that krealloc() succeeded (KASAN report is printed though). This patch adds an accessibility check into __do_krealloc(). If the check fails, krealloc() returns NULL. This check duplicates the one in ksize(); this is fixed in the following patch. This patch also adds a KASAN-KUnit test to check krealloc() behaviour when it's called on a freed object. Link: https://lkml.kernel.org/r/cbcf7b02be0a1ca11de4f833f2ff0b3f2c9b00c8.1612546384.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/test_kasan.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index e1bd1d1096de..e5647d147b35 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -353,6 +353,25 @@ static void krealloc_pagealloc_less_oob(struct kunit *test)
KMALLOC_MAX_CACHE_SIZE + 201);
}
+/*
+ * Check that krealloc() detects a use-after-free, returns NULL,
+ * and doesn't unpoison the freed object.
+ */
+static void krealloc_uaf(struct kunit *test)
+{
+ char *ptr1, *ptr2;
+ int size1 = 201;
+ int size2 = 235;
+
+ ptr1 = kmalloc(size1, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
+ kfree(ptr1);
+
+ KUNIT_EXPECT_KASAN_FAIL(test, ptr2 = krealloc(ptr1, size2, GFP_KERNEL));
+ KUNIT_ASSERT_PTR_EQ(test, (void *)ptr2, NULL);
+ KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)ptr1);
+}
+
static void kmalloc_oob_16(struct kunit *test)
{
struct {
@@ -1050,6 +1069,7 @@ static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(krealloc_less_oob),
KUNIT_CASE(krealloc_pagealloc_more_oob),
KUNIT_CASE(krealloc_pagealloc_less_oob),
+ KUNIT_CASE(krealloc_uaf),
KUNIT_CASE(kmalloc_oob_16),
KUNIT_CASE(kmalloc_uaf_16),
KUNIT_CASE(kmalloc_oob_in_memset),