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 BF3A1C433EF for ; Mon, 14 Feb 2022 10:41:25 +0000 (UTC) Received: from localhost ([::1]:36130 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nJYnM-0005a0-Dv for qemu-devel@archiver.kernel.org; Mon, 14 Feb 2022 05:41:24 -0500 Received: from eggs.gnu.org ([209.51.188.92]:46630) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nJYjL-0003Dl-1W for qemu-devel@nongnu.org; Mon, 14 Feb 2022 05:37:15 -0500 Received: from us-smtp-delivery-44.mimecast.com ([207.211.30.44]:32615) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nJYjI-0000OK-5c for qemu-devel@nongnu.org; Mon, 14 Feb 2022 05:37:14 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-361-3yZCuYQuN6C_Ex7e7cY3Xg-1; Mon, 14 Feb 2022 05:36:58 -0500 X-MC-Unique: 3yZCuYQuN6C_Ex7e7cY3Xg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9DA5C18A0F2A; Mon, 14 Feb 2022 10:36:56 +0000 (UTC) Received: from bahia (unknown [10.39.192.166]) by smtp.corp.redhat.com (Postfix) with ESMTP id 135625E4A5; Mon, 14 Feb 2022 10:36:54 +0000 (UTC) Date: Mon, 14 Feb 2022 11:36:53 +0100 From: Greg Kurz To: Christian Schoenebeck Subject: Re: [PULL 0/5] 9p queue 2022-02-10 Message-ID: <20220214113653.087a06e2@bahia> In-Reply-To: <2037112.271zI61438@silver> References: <2037112.271zI61438@silver> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kaod.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: softfail client-ip=207.211.30.44; envelope-from=groug@kaod.org; helo=us-smtp-delivery-44.mimecast.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.665, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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: , Cc: Vitaly Chikunov , Peter Maydell , qemu-devel@nongnu.org, "Dmitry V . Levin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 14 Feb 2022 10:47:43 +0100 Christian Schoenebeck wrote: > On Sonntag, 13. Februar 2022 21:33:10 CET Peter Maydell wrote: > > On Thu, 10 Feb 2022 at 11:33, Christian Schoenebeck > >=20 > > wrote: > > > The following changes since commit 0a301624c2f4ced3331ffd5bce85b4274f= e132af: > > > Merge remote-tracking branch > > > 'remotes/pmaydell/tags/pull-target-arm-20220208' into staging > > > (2022-02-08 11:40:08 +0000)>=20 > > > are available in the Git repository at: > > > https://github.com/cschoenebeck/qemu.git tags/pull-9p-20220210 > > >=20 > > > for you to fetch changes up to de19c79dad6a2cad54ae04ce754d47c07bf9bc= 93: > > > 9pfs: Fix segfault in do_readdir_many caused by struct dirent overr= ead > > > (2022-02-10 11:56:01 +0100)>=20 > > > ----------------------------------------------------------------9d82f= 6a3e68c2 > > > 9pfs: fixes and cleanup > > >=20 > > > * Fifth patch fixes a 9pfs server crash that happened on some systems= due > > >=20 > > > to incorrect (system dependant) handling of struct dirent size. > > >=20 > > > * Tests: Second patch fixes a test error that happened on some system= s due > > >=20 > > > mkdir() being called twice for creating the test directory for the = 9p > > > 'local' tests. > > >=20 > > > * Tests: Third patch fixes a memory leak. > > >=20 > > > * Tests: The remaining two patches are code cleanup. > > >=20 > > > ---------------------------------------------------------------- > >=20 > > Hi; this fails CI for the build-oss-fuzz job, which finds > > a heap-buffer-overflow: > > https://gitlab.com/qemu-project/qemu/-/jobs/2087610013 >=20 > So this is about the 'dirent' patch: > https://github.com/cschoenebeck/qemu/commit/de19c79dad6a2cad54ae04ce754d4= 7c07bf9bc93 >=20 > In conjunction with the 9p fuzzing tests: > https://wiki.qemu.org/Documentation/9p#Fuzzing >=20 > I first thought it might be a false positive due to the unorthodox handli= ng of > dirent duplication by that patch, but from the ASan output below I am not > really sure about that. >=20 No, this is an actual bug. See below. > Is there a way to get the content of local variables? >=20 > Would it be possible that the following issue (g_memdup vs. g_memdup2) mi= ght > apply here? > https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2= -now/5538 >=20 > Best regards, > Christian Schoenebeck >=20 > >=20 > > 8/152 qemu:qtest+qtest-i386 / qtest-i386/qos-test ERROR 66.74s killed > > by signal 6 SIGABRT > >=20 > > >>> QTEST_QEMU_BINARY=3D./qemu-system-i386 > > >>> QTEST_QEMU_STORAGE_DAEMON_BINARY=3D./storage-daemon/qemu-storage-da= emon > > >>> MALLOC_PERTURB_=3D120 > > >>> G_TEST_DBUS_DAEMON=3D/builds/qemu-project/qemu/tests/dbus-vmstate-d= aemon. > > >>> sh QTEST_QEMU_IMG=3D./qemu-img > > >>> /builds/qemu-project/qemu/build-oss-fuzz/tests/qtest/qos-test --tap= -k > > =E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80= =95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95= =E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2= =80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80= =95=E2=80=95=E2=80=95=E2=80=95=E2=80=95 =E2=9C=80 > > =E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80= =95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95= =E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2= =80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80=95=E2=80= =95=E2=80=95=E2=80=95=E2=80=95=E2=80=95 Listing only the last 100 lines fro= m > > a long log. > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D7270=3D=3DWARNING: ASan doesn't fully support makecontext/swapcon= text > > functions and may produce false positives in some cases! > > =3D=3D7270=3D=3DWARNING: ASan is ignoring requested __asan_handle_no_re= turn: > > stack type: default top: 0x7ffc79fb0000; bottom 0x7ff908ffd000; size: > > 0x000370fb3000 (14780411904) > > False positive error reports may follow > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D7276=3D=3DWARNING: ASan doesn't fully support makecontext/swapcon= text > > functions and may produce false positives in some cases! > > =3D=3D7276=3D=3DWARNING: ASan is ignoring requested __asan_handle_no_re= turn: > > stack type: default top: 0x7fff7e4a8000; bottom 0x7fd6363fd000; size: > > 0x0029480ab000 (177302319104) > > False positive error reports may follow > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D7282=3D=3DWARNING: ASan doesn't fully support makecontext/swapcon= text > > functions and may produce false positives in some cases! > > =3D=3D7282=3D=3DWARNING: ASan is ignoring requested __asan_handle_no_re= turn: > > stack type: default top: 0x7ffee6e7f000; bottom 0x7f32fb5fd000; size: > > 0x00cbeb882000 (875829927936) > > False positive error reports may follow > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D7288=3D=3DWARNING: ASan doesn't fully support makecontext/swapcon= text > > functions and may produce false positives in some cases! > > =3D=3D7288=3D=3DWARNING: ASan is ignoring requested __asan_handle_no_re= turn: > > stack type: default top: 0x7ffc6118e000; bottom 0x7f6391cfd000; size: > > 0x0098cf491000 (656312700928) > > False positive error reports may follow > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D7294=3D=3DWARNING: ASan doesn't fully support makecontext/swapcon= text > > functions and may produce false positives in some cases! > > =3D=3D7294=3D=3DWARNING: ASan is ignoring requested __asan_handle_no_re= turn: > > stack type: default top: 0x7ffef665d000; bottom 0x7f69dc8fd000; size: > > 0x009519d60000 (640383582208) > > False positive error reports may follow > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D7300=3D=3DWARNING: ASan doesn't fully support makecontext/swapcon= text > > functions and may produce false positives in some cases! > > =3D=3D7300=3D=3DWARNING: ASan is ignoring requested __asan_handle_no_re= turn: > > stack type: default top: 0x7ffe33db0000; bottom 0x7f01421fd000; size: > > 0x00fcf1bb3000 (1086387335168) > > False positive error reports may follow > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D7306=3D=3DWARNING: ASan doesn't fully support makecontext/swapcon= text > > functions and may produce false positives in some cases! > > =3D=3D7306=3D=3DWARNING: ASan is ignoring requested __asan_handle_no_re= turn: > > stack type: default top: 0x7ffebd618000; bottom 0x7ff1179fd000; size: > > 0x000da5c1b000 (58615508992) > > False positive error reports may follow > > For details see https://github.com/google/sanitizers/issues/189 > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > =3D=3D7306=3D=3DERROR: AddressSanitizer: heap-buffer-overflow on addres= s > > 0x612000030768 at pc 0x562351066c74 bp 0x7ff1078c3a90 sp > > 0x7ff1078c3240 > > READ of size 48830 at 0x612000030768 thread T4 The size looks pretty big to me. Test file paths in virtio-9p-test are only a couple of bytes long... > > #0 0x562351066c73 in __interceptor_memcpy.part.0 asan_interceptors.cpp.= o > > #1 0x7ff1290d443f in g_memdup (/lib64/libglib-2.0.so.0+0x6e43f) > > #2 0x56235134537a in do_readdir_many > > /builds/qemu-project/qemu/build-oss-fuzz/../hw/9pfs/codir.c:146:19 > > #3 0x56235134537a in v9fs_co_readdir_many > > /builds/qemu-project/qemu/build-oss-fuzz/../hw/9pfs/codir.c:225:5 > > #4 0x56235132d626 in v9fs_do_readdir > > /builds/qemu-project/qemu/build-oss-fuzz/../hw/9pfs/9p.c:2430:13 > > #5 0x56235132d626 in v9fs_readdir > > /builds/qemu-project/qemu/build-oss-fuzz/../hw/9pfs/9p.c:2543:13 > > #6 0x56235257101e in coroutine_trampoline > > /builds/qemu-project/qemu/build-oss-fuzz/../util/coroutine-ucontext.c:1= 73:9 > > #7 0x7ff126e0e84f (/lib64/libc.so.6+0x5784f) > > 0x612000030768 is located 0 bytes to the right of 296-byte region > > [0x612000030640,0x612000030768) > > allocated by thread T4 here: > > #0 0x5623510a4e47 in malloc > > (/builds/qemu-project/qemu/build-oss-fuzz/qemu-system-i386+0x1146e47) > > #1 0x7ff1290c03d8 in g_malloc (/lib64/libglib-2.0.so.0+0x5a3d8) i.e. synth_open =3D g_malloc(sizeof(*synth_open)); and we have: typedef struct V9fsSynthOpenState { off_t offset; V9fsSynthNode *node; struct dirent dent; } V9fsSynthOpenState; It looks like that qemu_dirent_dup() ends up using an uninitialized dent->d_reclen. The synth backend should be fixed to honor d_reclen, or at least to allocate with g_new0(). Cheers, -- Greg > > #2 0x56235131e659 in synth_opendir > > /builds/qemu-project/qemu/build-oss-fuzz/../hw/9pfs/9p-synth.c:185:18 > > #3 0x5623513462f5 in v9fs_co_opendir > > /builds/qemu-project/qemu/build-oss-fuzz/../hw/9pfs/codir.c:321:5 > > #4 0x5623513257d7 in v9fs_open > > /builds/qemu-project/qemu/build-oss-fuzz/../hw/9pfs/9p.c:1959:15 > > #5 0x56235257101e in coroutine_trampoline > > /builds/qemu-project/qemu/build-oss-fuzz/../util/coroutine-ucontext.c:1= 73:9 > > #6 0x7ff126e0e84f (/lib64/libc.so.6+0x5784f) > > Thread T4 created by T0 here: > > #0 0x562351015926 in pthread_create > > (/builds/qemu-project/qemu/build-oss-fuzz/qemu-system-i386+0x10b7926) > > #1 0x5623525351ea in qemu_thread_create > > /builds/qemu-project/qemu/build-oss-fuzz/../util/qemu-thread-posix.c:59= 6:11 > > #2 0x5623525a4588 in do_spawn_thread > > /builds/qemu-project/qemu/build-oss-fuzz/../util/thread-pool.c:134:5 > > #3 0x5623525a4588 in spawn_thread_bh_fn > > /builds/qemu-project/qemu/build-oss-fuzz/../util/thread-pool.c:142:5 > > #4 0x562352569814 in aio_bh_call > > /builds/qemu-project/qemu/build-oss-fuzz/../util/async.c:141:5 > > #5 0x562352569814 in aio_bh_poll > > /builds/qemu-project/qemu/build-oss-fuzz/../util/async.c:169:13 > > #6 0x5623525248cc in aio_dispatch > > /builds/qemu-project/qemu/build-oss-fuzz/../util/aio-posix.c:415:5 > > #7 0x56235256c34c in aio_ctx_dispatch > > /builds/qemu-project/qemu/build-oss-fuzz/../util/async.c:311:5 > > #8 0x7ff1290bb05e in g_main_context_dispatch > > (/lib64/libglib-2.0.so.0+0x5505e) SUMMARY: AddressSanitizer: > > heap-buffer-overflow > > asan_interceptors.cpp.o in __interceptor_memcpy.part.0 > > Shadow bytes around the buggy address: > > 0x0c247fffe090: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd > > 0x0c247fffe0a0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd > > 0x0c247fffe0b0: fd fd fd fd fd fd fd fd fd fd fd fd fd fa fa fa > > 0x0c247fffe0c0: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00 > > 0x0c247fffe0d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > =3D>0x0c247fffe0e0: 00 00 00 00 00 00 00 00 00 00 00 00 00[fa]fa fa > > 0x0c247fffe0f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > > 0x0c247fffe100: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > > 0x0c247fffe110: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > > 0x0c247fffe120: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > > 0x0c247fffe130: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > > Shadow byte legend (one shadow byte represents 8 application bytes): > > Addressable: 00 > > Partially addressable: 01 02 03 04 05 06 07 > > Heap left redzone: fa > > Freed heap region: fd > > Stack left redzone: f1 > > Stack mid redzone: f2 > > Stack right redzone: f3 > > Stack after return: f5 > > Stack use after scope: f8 > > Global redzone: f9 > > Global init order: f6 > > Poisoned by user: f7 > > Container overflow: fc > > Array cookie: ac > > Intra object redzone: bb > > ASan internal: fe > > Left alloca redzone: ca > > Right alloca redzone: cb > > =3D=3D7306=3D=3DABORTING > >=20 > >=20 > > thanks > > -- PMM >=20 >=20