From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DBF4EC433EF for ; Wed, 20 Apr 2022 22:08:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353494AbiDTWLi (ORCPT ); Wed, 20 Apr 2022 18:11:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241241AbiDTWLh (ORCPT ); Wed, 20 Apr 2022 18:11:37 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D3E11902A for ; Wed, 20 Apr 2022 15:08:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B9F34B821B6 for ; Wed, 20 Apr 2022 22:08:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73151C385A1; Wed, 20 Apr 2022 22:08:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1650492527; bh=sEBZVJsPT9ZiXXHLkv4qOzHJfJLVXw9y0HvruWjmlN0=; h=Date:To:From:Subject:From; b=CdzoSfgWZljFtut87zdFHt3DHBw3gAAr8FzCHEy2bsiyioTOwfPongIz59Ft+7vJJ /5jsi+Qaqs4KQHkyuhhmPfcqvvgLwrIg/kqtF/g+TB4oZ31tXkFIi4Ou4PwaGRBww2 U1dLIv2jdQCP98HuCbzIZKSP96cAQg8xGUCM9o6A= Date: Wed, 20 Apr 2022 15:08:46 -0700 To: mm-commits@vger.kernel.org, skhan@linuxfoundation.org, sidhartha.kumar@oracle.com, akpm@linux-foundation.org From: Andrew Morton Subject: + selftest-vm-verify-remap-destination-address-in-mremap_test.patch added to -mm tree Message-Id: <20220420220847.73151C385A1@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: selftest/vm: verify remap destination address in mremap_test has been added to the -mm tree. Its filename is selftest-vm-verify-remap-destination-address-in-mremap_test.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/selftest-vm-verify-remap-destination-address-in-mremap_test.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/selftest-vm-verify-remap-destination-address-in-mremap_test.patch 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 and is updated there every 3-4 working days ------------------------------------------------------ From: Sidhartha Kumar Subject: selftest/vm: verify remap destination address in mremap_test Because mremap does not have a MAP_FIXED_NOREPLACE flag, it can destroy existing mappings. This causes a segfault when regions such as text are remapped and the permissions are changed. Verify the requested mremap destination address does not overlap any existing mappings by using mmap's MAP_FIXED_NOREPLACE flag. Keep incrementing the destination address until a valid mapping is found or fail the current test once the max address is reached. Link: https://lkml.kernel.org/r/20220420215721.4868-2-sidhartha.kumar@oracle.com Signed-off-by: Sidhartha Kumar Cc: Shuah Khan Signed-off-by: Andrew Morton --- tools/testing/selftests/vm/mremap_test.c | 42 +++++++++++++++++++-- 1 file changed, 39 insertions(+), 3 deletions(-) --- a/tools/testing/selftests/vm/mremap_test.c~selftest-vm-verify-remap-destination-address-in-mremap_test +++ a/tools/testing/selftests/vm/mremap_test.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "../kselftest.h" @@ -64,6 +65,30 @@ enum { .expect_failure = should_fail \ } +/* + * Returns false if the requested remap region overlaps with an + * existing mapping (e.g text, stack) else returns true. + */ +static bool is_remap_region_valid(void *addr, unsigned long long size) +{ + void *remap_addr = NULL; + bool ret = true; + + /* Use MAP_FIXED_NOREPLACE flag to ensure region is not mapped */ + remap_addr = mmap(addr, size, PROT_READ | PROT_WRITE, + MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED, + -1, 0); + + if (remap_addr == MAP_FAILED) { + if (errno == EEXIST) + ret = false; + } else { + munmap(remap_addr, size); + } + + return ret; +} + /* Returns mmap_min_addr sysctl tunable from procfs */ static unsigned long long get_mmap_min_addr(void) { @@ -111,8 +136,8 @@ retry: goto retry; src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE, - MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED, - -1, 0); + MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED, + -1, 0); if (src_addr == MAP_FAILED) { if (errno == EPERM || errno == EEXIST) goto retry; @@ -179,9 +204,20 @@ static long long remap_region(struct con if (!((unsigned long long) addr & c.dest_alignment)) addr = (void *) ((unsigned long long) addr | c.dest_alignment); + /* Don't destroy existing mappings unless expected to overlap */ + while (!is_remap_region_valid(addr, c.region_size) && !c.overlapping) { + /* Check for unsigned overflow */ + if (addr + c.dest_alignment < addr) { + ksft_print_msg("Couldn't find a valid region to remap to\n"); + ret = -1; + goto out; + } + addr += c.dest_alignment; + } + clock_gettime(CLOCK_MONOTONIC, &t_start); dest_addr = mremap(src_addr, c.region_size, c.region_size, - MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr); + MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr); clock_gettime(CLOCK_MONOTONIC, &t_end); if (dest_addr == MAP_FAILED) { _ Patches currently in -mm which might be from sidhartha.kumar@oracle.com are selftest-vm-verify-mmap-addr-in-mremap_test.patch selftest-vm-verify-remap-destination-address-in-mremap_test.patch selftest-vm-support-xfail-in-mremap_test.patch selftest-vm-add-skip-support-to-mremap_test.patch selftest-vm-clarify-error-statement-in-gup_test.patch