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 78549C433EF for ; Tue, 10 May 2022 14:13:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343501AbiEJORw (ORCPT ); Tue, 10 May 2022 10:17:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244997AbiEJNrK (ORCPT ); Tue, 10 May 2022 09:47:10 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63BA0366BF; Tue, 10 May 2022 06:33:18 -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 sin.source.kernel.org (Postfix) with ESMTPS id A1249CE1EED; Tue, 10 May 2022 13:33:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADFCAC385A6; Tue, 10 May 2022 13:33:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652189595; bh=VYx/Qn1xfl7ARAKdkKF03gmmvh4hIEeI/UBBC2WRzgg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Uvj67X8ds7cZz88YjXPmXtUJIRCNMJJVlS+kqS1/u5G99jwkwF9yS2Vlx63X5m0B5 mUPaeJ+RjIKfiRb84G2dfF0fS9AdIVeJFG6cVGMzxmcvljoBWwYWv82dHGPfTUXIYT W/zuOoiEVZyUWqMb6NWCZNRjPjRiAoEZ8c/4AsPQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sidhartha Kumar , Shuah Khan , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.15 101/135] selftest/vm: verify remap destination address in mremap_test Date: Tue, 10 May 2022 15:08:03 +0200 Message-Id: <20220510130743.305503241@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220510130740.392653815@linuxfoundation.org> References: <20220510130740.392653815@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sidhartha Kumar [ Upstream commit 18d609daa546c919fd36b62a7b510c18de4b4af8 ] 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 Reviewed-by: Shuah Khan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- tools/testing/selftests/vm/mremap_test.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c index efcbf537b3d5..8f4dbbd60c09 100644 --- a/tools/testing/selftests/vm/mremap_test.c +++ b/tools/testing/selftests/vm/mremap_test.c @@ -66,6 +66,30 @@ 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) { -- 2.35.1