From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2D73D18DF9E for ; Thu, 10 Oct 2024 21:00:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728594035; cv=none; b=ulsoj5ptEEgDMUDIueTwXuNW26ps/wic2NOxolLI3M42Z9ELRMcv5EsVT42rUdEaRSVwaCAUPfKuSID/xgedEcAzf1b7l1isFmWTD3j2yg6oFAHKjFLArYW5lLyCQEFIdF5oPhKLWcwpOPh8lc+pCdAedG9/qOULKuktyXV8q5o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728594035; c=relaxed/simple; bh=UwrbvSlK0z8I1oU1VLKqVUBNeh9KwYuHsRKPRlnW628=; h=Date:To:From:Subject:Message-Id; b=n94H9tlWGgZ35gnv1pSGE0e64HbeG0N3VdrQsIY0HKdL00CSTNHfYgVGntRgF+uLSfhTia+COGK0vrCMqgu4iU0kS+VVjYhIr8BKhdPHNkylSwGIpE3LWkZrnf4DKp6rRS0bPY2iBF/zvnic/YxasSsQT6f1SEC7LkXHdx2h6VA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=uihUm8pb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="uihUm8pb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E03BC4CEC5; Thu, 10 Oct 2024 21:00:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1728594034; bh=UwrbvSlK0z8I1oU1VLKqVUBNeh9KwYuHsRKPRlnW628=; h=Date:To:From:Subject:From; b=uihUm8pbPPAW8rYos3mVzCKoh/nlE7rtF5pm7m1x3DgwgS/a3b0dSl3gxlZ0SUVMC kHYkPrLTgiPze7fJjdohWuh7IVi6tlWpM/U37hlmb6VrmYC0nYEAoOpK4vc9ItJJbQ dpy99Re0zvBAM6MHF6yK1bI3wBOkIpgAOOnSC22g= Date: Thu, 10 Oct 2024 14:00:34 -0700 To: mm-commits@vger.kernel.org,vincenzo.frascino@arm.com,ryabinin.a.a@gmail.com,glider@google.com,elver@google.com,dvyukov@google.com,andreyknvl@gmail.com,snovitoll@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-kasan-kmsan-copy_from-to_kernel_nofault.patch added to mm-unstable branch Message-Id: <20241010210034.9E03BC4CEC5@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm, kasan, kmsan: copy_from/to_kernel_nofault has been added to the -mm mm-unstable branch. Its filename is mm-kasan-kmsan-copy_from-to_kernel_nofault.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-kasan-kmsan-copy_from-to_kernel_nofault.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Sabyrzhan Tasbolatov Subject: mm, kasan, kmsan: copy_from/to_kernel_nofault Date: Thu, 10 Oct 2024 18:11:30 +0500 Instrument copy_from_kernel_nofault() with KMSAN for uninitialized kernel memory check and copy_to_kernel_nofault() with KASAN, KCSAN to detect the memory corruption. syzbot reported that bpf_probe_read_kernel() kernel helper triggered KASAN report via kasan_check_range() which is not the expected behaviour as copy_from_kernel_nofault() is meant to be a non-faulting helper. Solution is, suggested by Marco Elver, to replace KASAN, KCSAN check in copy_from_kernel_nofault() with KMSAN detection of copying uninitilaized kernel memory. In copy_to_kernel_nofault() we can retain instrument_write() explicitly for the memory corruption instrumentation. copy_to_kernel_nofault() is tested on x86_64 and arm64 with CONFIG_KASAN_SW_TAGS. On arm64 with CONFIG_KASAN_HW_TAGS, kunit test currently fails. Need more clarification on it. Link: https://lore.kernel.org/linux-mm/CANpmjNMAVFzqnCZhEity9cjiqQ9CVN1X7qeeeAp_6yKjwKo8iw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20241010131130.2903601-1-snovitoll@gmail.com Signed-off-by: Sabyrzhan Tasbolatov Suggested-by: Marco Elver Reviewed-by: Marco Elver Reported-by: syzbot+61123a5daeb9f7454599@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=61123a5daeb9f7454599 Reported-by: Andrey Konovalov Closes: https://bugzilla.kernel.org/show_bug.cgi?id=210505 Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Vincenzo Frascino Signed-off-by: Andrew Morton --- mm/kasan/kasan_test_c.c | 37 +++++++++++++++++++++++++++++++++++++ mm/kmsan/kmsan_test.c | 17 +++++++++++++++++ mm/maccess.c | 10 ++++++++-- 3 files changed, 62 insertions(+), 2 deletions(-) --- a/mm/kasan/kasan_test_c.c~mm-kasan-kmsan-copy_from-to_kernel_nofault +++ a/mm/kasan/kasan_test_c.c @@ -1954,6 +1954,42 @@ static void rust_uaf(struct kunit *test) KUNIT_EXPECT_KASAN_FAIL(test, kasan_test_rust_uaf()); } +static void copy_to_kernel_nofault_oob(struct kunit *test) +{ + char *ptr; + char buf[128]; + size_t size = sizeof(buf); + + /* This test currently fails with the HW_TAGS mode. + * The reason is unknown and needs to be investigated. */ + ptr = kmalloc(size - KASAN_GRANULE_SIZE, GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + OPTIMIZER_HIDE_VAR(ptr); + + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) { + /* 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); + } + + /* + * We test copy_to_kernel_nofault() to detect corrupted memory that is + * being written into the kernel. In contrast, copy_from_kernel_nofault() + * is primarily used in kernel helper functions where the source address + * might be random or uninitialized. Applying KASAN instrumentation to + * copy_from_kernel_nofault() could lead to false positives. + * By focusing KASAN checks only on copy_to_kernel_nofault(), + * we ensure that only valid memory is written to the kernel, + * minimizing the risk of kernel corruption while avoiding + * false positives in the reverse case. + */ + KUNIT_EXPECT_KASAN_FAIL(test, + copy_to_kernel_nofault(&buf[0], ptr, size)); + KUNIT_EXPECT_KASAN_FAIL(test, + copy_to_kernel_nofault(ptr, &buf[0], size)); + kfree(ptr); +} + static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kmalloc_oob_right), KUNIT_CASE(kmalloc_oob_left), @@ -2027,6 +2063,7 @@ static struct kunit_case kasan_kunit_tes KUNIT_CASE(match_all_not_assigned), KUNIT_CASE(match_all_ptr_tag), KUNIT_CASE(match_all_mem_tag), + KUNIT_CASE(copy_to_kernel_nofault_oob), KUNIT_CASE(rust_uaf), {} }; --- a/mm/kmsan/kmsan_test.c~mm-kasan-kmsan-copy_from-to_kernel_nofault +++ a/mm/kmsan/kmsan_test.c @@ -640,6 +640,22 @@ static void test_unpoison_memory(struct KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } +static void test_copy_from_kernel_nofault(struct kunit *test) +{ + long ret; + char buf[4], src[4]; + size_t size = sizeof(buf); + + EXPECTATION_UNINIT_VALUE_FN(expect, "copy_from_kernel_nofault"); + kunit_info( + test, + "testing copy_from_kernel_nofault with uninitialized memory\n"); + + ret = copy_from_kernel_nofault((char *)&buf[0], (char *)&src[0], size); + USE(ret); + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); +} + static struct kunit_case kmsan_test_cases[] = { KUNIT_CASE(test_uninit_kmalloc), KUNIT_CASE(test_init_kmalloc), @@ -664,6 +680,7 @@ static struct kunit_case kmsan_test_case KUNIT_CASE(test_long_origin_chain), KUNIT_CASE(test_stackdepot_roundtrip), KUNIT_CASE(test_unpoison_memory), + KUNIT_CASE(test_copy_from_kernel_nofault), {}, }; --- a/mm/maccess.c~mm-kasan-kmsan-copy_from-to_kernel_nofault +++ a/mm/maccess.c @@ -13,9 +13,14 @@ bool __weak copy_from_kernel_nofault_all return true; } +/* + * The below only uses kmsan_check_memory() to ensure uninitialized kernel + * memory isn't leaked. + */ #define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \ while (len >= sizeof(type)) { \ - __get_kernel_nofault(dst, src, type, err_label); \ + __get_kernel_nofault(dst, src, type, err_label); \ + kmsan_check_memory(src, sizeof(type)); \ dst += sizeof(type); \ src += sizeof(type); \ len -= sizeof(type); \ @@ -49,7 +54,8 @@ EXPORT_SYMBOL_GPL(copy_from_kernel_nofau #define copy_to_kernel_nofault_loop(dst, src, len, type, err_label) \ while (len >= sizeof(type)) { \ - __put_kernel_nofault(dst, src, type, err_label); \ + __put_kernel_nofault(dst, src, type, err_label); \ + instrument_write(dst, sizeof(type)); \ dst += sizeof(type); \ src += sizeof(type); \ len -= sizeof(type); \ _ Patches currently in -mm which might be from snovitoll@gmail.com are mm-kasan-kmsan-copy_from-to_kernel_nofault.patch