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 X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F5F2C43441 for ; Tue, 13 Nov 2018 20:40:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5848224E0 for ; Tue, 13 Nov 2018 20:40:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E5848224E0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728261AbeKNGkb (ORCPT ); Wed, 14 Nov 2018 01:40:31 -0500 Received: from mx2.suse.de ([195.135.220.15]:54940 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725750AbeKNGkb (ORCPT ); Wed, 14 Nov 2018 01:40:31 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1496DAFF6; Tue, 13 Nov 2018 20:40:38 +0000 (UTC) From: NeilBrown To: Jeff Layton , syzbot , bfields@fieldses.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Date: Wed, 14 Nov 2018 07:40:22 +1100 Cc: Neil Brown Subject: Re: KASAN: use-after-free Read in locks_delete_block In-Reply-To: <9d9ad7f2781bf15af4bd6ccc9feee35c7cd17979.camel@kernel.org> References: <000000000000222b58057a7d9f39@google.com> <9d9ad7f2781bf15af4bd6ccc9feee35c7cd17979.camel@kernel.org> Message-ID: <87bm6svhhl.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, Nov 13 2018, Jeff Layton wrote: > On Mon, 2018-11-12 at 12:34 -0800, syzbot wrote: >> Hello, >>=20 >> syzbot found the following crash on: >>=20 >> HEAD commit: 442b8cea2477 Add linux-next specific files for 20181109 >> git tree: linux-next >> console output: https://syzkaller.appspot.com/x/log.txt?x=3D115dbad54000= 00 >> kernel config: https://syzkaller.appspot.com/x/.config?x=3D2f72bdb11df9= fbe8 >> dashboard link: https://syzkaller.appspot.com/bug?extid=3Da4a3d526b41571= 13ec6a >> compiler: gcc (GCC) 8.0.1 20180413 (experimental) >>=20 >> Unfortunately, I don't have any reproducer for this crash yet. >>=20 >> IMPORTANT: if you fix the bug, please add the following tag to the commi= t: >> Reported-by: syzbot+a4a3d526b4157113ec6a@syzkaller.appspotmail.com >>=20 >> device loop0 blocksize: 4096 >> __find_get_block_slow() failed. block=3D1, b_blocknr=3D8 >> b_state=3D0x00000029, b_size=3D512 >> device loop0 blocksize: 4096 >> =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 >> BUG: KASAN: use-after-free in __list_del_entry_valid+0xf1/0x100=20=20 >> lib/list_debug.c:51 >> Read of size 8 at addr ffff88017eb47b70 by task syz-executor3/13461 >>=20 >> CPU: 0 PID: 13461 Comm: syz-executor3 Not tainted 4.20.0-rc1-next-201811= 09+=20=20 >> #110 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS= =20=20 >> Google 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x244/0x39d lib/dump_stack.c:113 >> print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 >> kasan_report_error mm/kasan/report.c:354 [inline] >> kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412 >> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 >> __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51 >> __list_del_entry include/linux/list.h:117 [inline] >> list_del_init include/linux/list.h:159 [inline] >> __locks_delete_block fs/locks.c:683 [inline] >> locks_delete_block+0xce/0x3d0 fs/locks.c:716 >> locks_mandatory_area+0x48b/0x6a0 fs/locks.c:1398 >> rw_verify_area+0x2f2/0x360 fs/read_write.c:386 >> vfs_write+0x149/0x560 fs/read_write.c:544 >> ksys_write+0x101/0x260 fs/read_write.c:598 >> __do_sys_write fs/read_write.c:610 [inline] >> __se_sys_write fs/read_write.c:607 [inline] >> __x64_sys_write+0x73/0xb0 fs/read_write.c:607 >> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> RIP: 0033:0x457569 >> Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 = f7=20=20 >> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 f= f=20=20 >> ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 >> RSP: 002b:00007ff2e8194c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 >> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569 >> RDX: 0000000000000010 RSI: 0000000020000180 RDI: 0000000000000006 >> RBP: 000000000072c0e0 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff2e81956d4 >> R13: 00000000004c571f R14: 00000000004d9360 R15: 00000000ffffffff >>=20 >> The buggy address belongs to the page: >> page:ffffea0005fad1c0 count:0 mapcount:0 mapping:0000000000000000 index:= 0x0 >> flags: 0x2fffc0000000000() >> raw: 02fffc0000000000 0000000000000000 ffffea0005fad1c8 0000000000000000 >> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >> page dumped because: kasan: bad access detected >>=20 >> Memory state around the buggy address: >> ffff88017eb47a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ffff88017eb47a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> > ffff88017eb47b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>=20 >> ^ >> ffff88017eb47b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ffff88017eb47c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> =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 >>=20 > > Ouch, crash down in the mandatory locking code. This is with Neil's set > from last week. I haven't merged the series he sent the other day yet, > but they don't seem to be different in this regard. > > Looks like the fl_blocked list might have had an entry on it that was > freed without being removed? locks_mandatory_area declares a file_lock > on the stack, but it seems to be initialized properly. > > The one weird thing is that locks_mandatory_area sets FL_ACCESS and > FL_SLEEP, but I don't see anything wrong with that right offhand. > > Neil, any thoughts? I'm not certain, but probably this: From: NeilBrown Date: Wed, 14 Nov 2018 07:38:05 +1100 Subject: [PATCH] fs/locks: always delete_block after waiting - mandatory lo= cks The patch fs/locks: always delete_block after waiting. should have moved the locks_delete_block() call in locks_mandatory_area() too. This might fix the bug: Reported-by: syzbot+a4a3d526b4157113ec6a@syzkaller.appspotmail.com Signed-off-by: NeilBrown =2D-- fs/locks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/locks.c b/fs/locks.c index f456cd3d9d50..eb0c0b33fb7b 100644 =2D-- a/fs/locks.c +++ b/fs/locks.c @@ -1436,9 +1436,9 @@ int locks_mandatory_area(struct inode *inode, struct = file *filp, loff_t start, continue; } =20 =2D locks_delete_block(&fl); break; } + locks_delete_block(&fl); =20 return error; } =2D-=20 2.14.0.rc0.dirty --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlvrNrcACgkQOeye3VZi gbkLUw/9Ft7k7AaNK9bCbGy0hPy30Y6lmaLxlgVr58SGAYH1Xc0/KbIJFY5WbJVa IXOsew5VsEqwMWNjqH0XkOvQ8NWgjEC9f16h3gblsVpmcz7uj4AKw10JJXXKVk9m qgogMTpeKv9+SivG0kfgOs4+OkvrnFq1v6T5BUPXKr5ki7HIcjjxc0fL/hktDtwH GP6J8Wj7ONXSA4la/xiNt5FrWmlKTqv2UDGqIpWjtV3pZcDbGcrtZvx4XSy9ZHit yi6BZrcY6RcLyJz8ru4DJs6NmJfags9ZIGm9aAMGgaYs9hWCfTuCOBIR5Rc4fNPC jU7zkmfXf27Mu/O+GWGRR0JIM9pa9qIuasp0ktSosBH1Gz+ebMug6weuYWW1Z1SN wDHCEK9riI3Q6CQ9SEV1s2hVAdeinVXh0BkhJzy91a7okoodCEg5R8Y0Te4Yg4Oc CJ2IInHmoGDIVy+9EqinqPipZ1N0radiBa16OuIdWrYKAX/fcxmEAERnDjVoNc7Y 6/+owTkt7La89h0Yny4c11VgXWRxYQwN/eJhDBFzDA4GklXlzjYD4kTGCUesMKo3 bmuuLQJJsAGQOyJPvngtpc7KzX+Q8GhIeMrI0Dv6JZL58i6+UugI8cNImh9HKU+z XTwBALIl23iWXS5d4JVPPfcxsLlTtkiCo6kZ3bZwEXxDbWoyLdk= =Y0bO -----END PGP SIGNATURE----- --=-=-=--