Thank you for the update. On 11/15/24 12:19, Andrew Morton wrote:
The quilt patch titled Subject: mm/kfence: add a new kunit test test_use_after_free_read_nofault() has been removed from the -mm tree. Its filename was mm-kfence-add-a-new-kunit-test-test_use_after_free_read_nofault.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Nirjhar Roy <nirjhar@xxxxxxxxxxxxx> Subject: mm/kfence: add a new kunit test test_use_after_free_read_nofault() Date: Fri, 18 Oct 2024 23:16:01 +0530 Faults from copy_from_kernel_nofault() need to be handled by fixup table and should not be handled by kfence. Otherwise while reading /proc/kcore which uses copy_from_kernel_nofault(), kfence can generate false negatives. This can happen when /proc/kcore ends up reading an unmapped address from kfence pool. Let's add a testcase to cover this case. Link: https://lkml.kernel.org/r/210e561f7845697a32de44b643393890f180069f.1729272697.git.ritesh.list@xxxxxxxxx Signed-off-by: Nirjhar Roy <nirjhar@xxxxxxxxxxxxx> Co-developed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> Tested-by: Marco Elver <elver@xxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kfence/kfence_test.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) --- a/mm/kfence/kfence_test.c~mm-kfence-add-a-new-kunit-test-test_use_after_free_read_nofault +++ a/mm/kfence/kfence_test.c @@ -383,6 +383,22 @@ static void test_use_after_free_read(str KUNIT_EXPECT_TRUE(test, report_matches(&expect)); }+static void test_use_after_free_read_nofault(struct kunit *test)+{ + const size_t size = 32; + char *addr; + char dst; + int ret; + + setup_test_cache(test, size, 0, NULL); + addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY); + test_free(addr); + /* Use after free with *_nofault() */ + ret = copy_from_kernel_nofault(&dst, addr, 1); + KUNIT_EXPECT_EQ(test, ret, -EFAULT); + KUNIT_EXPECT_FALSE(test, report_available()); +} + static void test_double_free(struct kunit *test) { const size_t size = 32; @@ -780,6 +796,7 @@ static struct kunit_case kfence_test_cas KFENCE_KUNIT_CASE(test_out_of_bounds_read), KFENCE_KUNIT_CASE(test_out_of_bounds_write), KFENCE_KUNIT_CASE(test_use_after_free_read), + KFENCE_KUNIT_CASE(test_use_after_free_read_nofault), KFENCE_KUNIT_CASE(test_double_free), KFENCE_KUNIT_CASE(test_invalid_addr_free), KFENCE_KUNIT_CASE(test_corruption), _ Patches currently in -mm which might be from nirjhar@xxxxxxxxxxxxx are
-- --- Nirjhar Roy Linux Kernel Developer IBM, Bangalore
