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 8D928C4167B for ; Tue, 8 Nov 2022 19:52:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229742AbiKHTws (ORCPT ); Tue, 8 Nov 2022 14:52:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229645AbiKHTwq (ORCPT ); Tue, 8 Nov 2022 14:52:46 -0500 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 28AFE65E6C; Tue, 8 Nov 2022 11:52:46 -0800 (PST) Received: from pwmachine.numericable.fr (85-170-25-210.rev.numericable.fr [85.170.25.210]) by linux.microsoft.com (Postfix) with ESMTPSA id C085920B9F80; Tue, 8 Nov 2022 11:52:41 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com C085920B9F80 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1667937165; bh=t36xpm43qmLMEEXsLNHAnvSSN1fHn9/wxZfzoHQm4H4=; h=From:To:Cc:Subject:Date:From; b=jLCsIjthGu7d4DRVQ1TB1mUyc8RViDwSi21b47OLSSvYIUrMF88SfAwGaztkyEF3C xlvS4iAXH5LWDmr/3H9Zbx7JkO/Pk1Yeyq1fUOTIm7LLa854J4p4OteAabn/akYUnt ut53qaPtrmCoJUQjxqsEupHjc9whVtslOLdkiBus= From: Francis Laniel To: linux-kernel@vger.kernel.org Cc: Alban Crequy , Francis Laniel , Andrew Morton , Andrii Nakryiko , Mykola Lysenko , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Alban Crequy , linux-mm@kvack.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [RFC PATCH v1 0/2] Fix offset when fault occurs in strncpy_from_kernel_nofault() Date: Tue, 8 Nov 2022 20:52:05 +0100 Message-Id: <20221108195211.214025-1-flaniel@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi. First of all, I hope you are fine and the same for your relatives. This contribution fixes a bug where the byte before the destination address can be reset when a page fault occurs in strncpy_from_kernel_nofault() while copying the first byte from the source address. This bug leaded to kernel panic if a pointer containing the modified address is dereferenced as the pointer does not contain a correct addresss. To fix this bug, we simply reset the current destination byte in a case of a page fault. The proposed fix was tested and validated inside a VM: root@vm-amd64:~# ./share/linux/tools/testing/selftests/bpf/test_progs --name varlen ... #222 varlen:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED Without the patch, the test will fail: root@vm-amd64:~# ./share/linux/tools/testing/selftests/bpf/test_progs --name varlen ... #222 varlen:FAIL Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED If you see any way to improve this contribution, feel free to share. Alban Crequy (2): maccess: fix writing offset in case of fault in strncpy_from_kernel_nofault() selftests: bpf: add a test when bpf_probe_read_kernel_str() returns EFAULT mm/maccess.c | 2 +- tools/testing/selftests/bpf/prog_tests/varlen.c | 7 +++++++ tools/testing/selftests/bpf/progs/test_varlen.c | 5 +++++ 3 files changed, 13 insertions(+), 1 deletion(-) Best regards and thank you in advance. -- 2.25.1