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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 57356C433EF for ; Wed, 2 Feb 2022 17:59:07 +0000 (UTC) Received: from localhost ([::1]:46084 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nFJuL-0004iU-UO for qemu-devel@archiver.kernel.org; Wed, 02 Feb 2022 12:59:05 -0500 Received: from eggs.gnu.org ([209.51.188.92]:44930) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nFIvM-0002Ly-MP; Wed, 02 Feb 2022 11:56:04 -0500 Received: from kylie.crudebyte.com ([5.189.157.229]:35895) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nFIv7-0000VD-Ms; Wed, 02 Feb 2022 11:55:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=kylie; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Content-ID:Content-Description; bh=ULtCxNs//n9ZMEmRCIvPLZBHi9Bdb8xa3sonQ72zdN8=; b=NmSHqc6TFdqY7e5vHJjwkEfTHY HqQ9OakAshbbl4wYO6t/UGNS3zfq1jcE00chCXD40mrxB/wbN1/EI+n/FKpzO7PnmRtw6NFi3NodO rw3LZ10epXOxd161tzFq6774PPpCzvl80KkCcfpxmZSM1Oc2i0TUlvb5lyyRoA6426ISmMY2lAGHG xO3HUq98/4HrwyxGOnLjfr+YMAK4UJeg43HTGujmccs9UBZyzTDZIBoRml/sed1h84okU1HfS5slE FYGKlpn94DvJ4yZDLJOo2fb6h2AkqvKrT4x9Ye+7GfZ9ZgWIi2zb1AcyJhmaaoxunt2wQMYbRov5e X/6raADvqDa+nuXwb2fIDNKw5D0Y1TMRHZIM8fzJDgznmITox4VJw0PXQvaQ/GJ54d6/flKXAe3hX jfjO1Jv/8eV4ZsYECj2waqCgm9qJZKKNZ9MKH2UBcjU92hzIDP26yAKtou6mYl07eno2cwwbLGRPN JM/K6L+IDtzgFIne4l2FQBh1m07Y9jeQkWN+VErcomXIjT9XkAD3HmWpMJzBD1oAhAgPl8OAZHJ+e GKxgjwOOQ5JzTr3zwpYw85by4Yw671sj/jsD1YrJJ7lE4I1PmezPtrDgLH/PjpKltjQSNYMEp7Gym pe9Yfh1WPoXY+7DyxBEtdxul01xhbj1PBcJtHK1ls=; From: Christian Schoenebeck To: qemu-devel@nongnu.org Cc: Vitaly Chikunov , Greg Kurz , qemu-stable@nongnu.org, ldv@altlinux.org Subject: Re: [PATCH v2] 9pfs: Fix segfault in do_readdir_many caused by struct dirent overread Date: Wed, 02 Feb 2022 17:55:45 +0100 Message-ID: <2369945.Qq089p3Et8@silver> In-Reply-To: <20220128223326.927132-1-vt@altlinux.org> References: <20220128223326.927132-1-vt@altlinux.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Received-SPF: pass client-ip=5.189.157.229; envelope-from=qemu_oss@crudebyte.com; helo=kylie.crudebyte.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Freitag, 28. Januar 2022 23:33:26 CET Vitaly Chikunov wrote: > `struct dirent' returned from readdir(3) could be shorter than > `sizeof(struct dirent)', thus memcpy of sizeof length will overread > into unallocated page causing SIGSEGV. Example stack trace: > > #0 0x00005555559ebeed v9fs_co_readdir_many (/usr/bin/qemu-system-x86_64 + > 0x497eed) #1 0x00005555559ec2e9 v9fs_readdir (/usr/bin/qemu-system-x86_64 > + 0x4982e9) #2 0x0000555555eb7983 coroutine_trampoline > (/usr/bin/qemu-system-x86_64 + 0x963983) #3 0x00007ffff73e0be0 n/a (n/a + > 0x0) > > While fixing, provide a helper for any future `struct dirent' cloning. > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/841 > Cc: qemu-stable@nongnu.org > Co-authored-by: Christian Schoenebeck > Signed-off-by: Vitaly Chikunov > --- > Tested on x86-64 Linux. I was too optimistic. Looks like this needs more work. With this patch applied the 9p test cases [1] are crashing now: $ gdb --args tests/qtest/qos-test -m slow ... # Start of flush tests ok 50 /x86_64/pc/i440FX-pcihost/pci-bus-pc/pci-bus/virtio-9p-pci/virtio-9p/virtio-9p-tests/synth/flush/success ok 51 /x86_64/pc/i440FX-pcihost/pci-bus-pc/pci-bus/virtio-9p-pci/virtio-9p/virtio-9p-tests/synth/flush/ignored # End of flush tests # Start of readdir tests Broken pipe Thread 1 "qos-test" received signal SIGABRT, Aborted. __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 50 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory. (gdb) bt #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x00007ffff7b7d537 in __GI_abort () at abort.c:79 #2 0x00005555555ba495 in qtest_client_socket_recv_line (s=0x5555557663c0) at ../tests/qtest/libqtest.c:503 #3 0x00005555555ba5b3 in qtest_rsp_args (s=0x5555557663c0, expected_args=2) at ../tests/qtest/libqtest.c:523 #4 0x00005555555bbdb4 in qtest_clock_rsp (s=0x5555557663c0) at ../tests/qtest/libqtest.c:970 #5 0x00005555555bbe55 in qtest_clock_step (s=0x5555557663c0, step=100) at ../tests/qtest/libqtest.c:985 #6 0x00005555555cdc21 in qvirtio_wait_used_elem (qts=0x5555557663c0, d=0x555555779b48, vq=0x5555557b0480, desc_idx=8, len=0x0, timeout_us=10000000) at ../tests/qtest/libqos/virtio.c:220 #7 0x00005555555ae79f in v9fs_req_wait_for_reply (req=0x5555557899a0, len=0x0) at ../tests/qtest/virtio-9p-test.c:278 #8 0x00005555555b03bf in fs_readdir (obj=0x555555779bb0, data=0x0, t_alloc=0x5555557448b8) at ../tests/qtest/virtio-9p-test.c:851 #9 0x00005555555990c4 in run_one_test (arg=0x5555557ac600) at ../tests/qtest/qos-test.c:182 #10 0x00007ffff7f02b9e in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #11 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #12 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #13 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #14 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #15 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #16 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #17 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #18 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #19 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #20 0x00007ffff7f0299b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #21 0x00007ffff7f0308a in g_test_run_suite () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #22 0x00007ffff7f030a1 in g_test_run () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #23 0x00005555555995a3 in main (argc=1, argv=0x7fffffffe508, envp=0x7fffffffe528) at ../tests/qtest/qos-test.c:338 (gdb) [1] https://wiki.qemu.org/Documentation/9p#Test_Cases Best regards, Christian Schoenebeck