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 2B9F9C7EE29 for ; Sun, 4 Jun 2023 18:32:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229904AbjFDScY (ORCPT ); Sun, 4 Jun 2023 14:32:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229578AbjFDScX (ORCPT ); Sun, 4 Jun 2023 14:32:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 343B9AB for ; Sun, 4 Jun 2023 11:32:22 -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 dfw.source.kernel.org (Postfix) with ESMTPS id A4E3460C34 for ; Sun, 4 Jun 2023 18:32:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0D322C433EF; Sun, 4 Jun 2023 18:32:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1685903541; bh=yd8N7docz46jhXslvXDNZ+9apbHEajgXNVaQ0Ep6v5I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rNkvZSNFkDB6vZd90Ooj6Jq15xrd3y7G9KpGDgJgsDVwjGPKPJlGnnW82q1dvFbFY Lh+WhAo4fKaj2u4WokNm8zPEnp93IGRJLox/GeeT0CpK8QJRHNovfuln6fnTVSjfIN wNozvkKdiEXmi1qtKskjEj5+LSG8/7VK+T28BNO65hha/T19l7I62dd0lTRGhRCQAw Q+bHhM5X0ZIgW18c4erzcIFG+kI3YOQuF/AyYYcf2VQGcBdf6Cvh4BjCK31WFWlTqj 2XoLdoN6PNlYynEBs4xGMF066Ta2oiCgzjUnCHnNZ1O7t2B36rMCBZehk8s+ek3GCg MDMY244/AGMtw== Date: Sun, 4 Jun 2023 11:32:20 -0700 From: "Darrick J. Wong" To: Amir Goldstein Cc: Lee Jones , linux-xfs@vger.kernel.org, Dave Chinner , Leah Rumancik , Chandan Babu R Subject: Re: [PATCH] xfs: verify buffer contents when we skip log replay Message-ID: <20230604183220.GA72267@frogsfrogsfrogs> References: <20230411233159.GH360895@frogsfrogsfrogs> <20230601130351.GA1787684@google.com> <20230601151146.GH16865@frogsfrogsfrogs> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Sun, Jun 04, 2023 at 08:51:16AM +0300, Amir Goldstein wrote: > On Thu, Jun 1, 2023 at 6:18 PM Darrick J. Wong wrote: > > > > On Thu, Jun 01, 2023 at 02:03:51PM +0100, Lee Jones wrote: > > > Hi Darrick, > > > > > > On Tue, 11 Apr 2023, Darrick J. Wong wrote: > > > > > > > From: Darrick J. Wong > > > > > > > > syzbot detected a crash during log recovery: > > > > > > > > XFS (loop0): Mounting V5 Filesystem bfdc47fc-10d8-4eed-a562-11a831b3f791 > > > > XFS (loop0): Torn write (CRC failure) detected at log block 0x180. Truncating head block from 0x200. > > > > XFS (loop0): Starting recovery (logdev: internal) > > > > ================================================================== > > > > BUG: KASAN: slab-out-of-bounds in xfs_btree_lookup_get_block+0x15c/0x6d0 fs/xfs/libxfs/xfs_btree.c:1813 > > > > Read of size 8 at addr ffff88807e89f258 by task syz-executor132/5074 > > > > > > > > CPU: 0 PID: 5074 Comm: syz-executor132 Not tainted 6.2.0-rc1-syzkaller #0 > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 > > > > Call Trace: > > > > > > > > __dump_stack lib/dump_stack.c:88 [inline] > > > > dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106 > > > > print_address_description+0x74/0x340 mm/kasan/report.c:306 > > > > print_report+0x107/0x1f0 mm/kasan/report.c:417 > > > > kasan_report+0xcd/0x100 mm/kasan/report.c:517 > > > > xfs_btree_lookup_get_block+0x15c/0x6d0 fs/xfs/libxfs/xfs_btree.c:1813 > > > > xfs_btree_lookup+0x346/0x12c0 fs/xfs/libxfs/xfs_btree.c:1913 > > > > xfs_btree_simple_query_range+0xde/0x6a0 fs/xfs/libxfs/xfs_btree.c:4713 > > > > xfs_btree_query_range+0x2db/0x380 fs/xfs/libxfs/xfs_btree.c:4953 > > > > xfs_refcount_recover_cow_leftovers+0x2d1/0xa60 fs/xfs/libxfs/xfs_refcount.c:1946 > > > > xfs_reflink_recover_cow+0xab/0x1b0 fs/xfs/xfs_reflink.c:930 > > > > xlog_recover_finish+0x824/0x920 fs/xfs/xfs_log_recover.c:3493 > > > > xfs_log_mount_finish+0x1ec/0x3d0 fs/xfs/xfs_log.c:829 > > > > xfs_mountfs+0x146a/0x1ef0 fs/xfs/xfs_mount.c:933 > > > > xfs_fs_fill_super+0xf95/0x11f0 fs/xfs/xfs_super.c:1666 > > > > get_tree_bdev+0x400/0x620 fs/super.c:1282 > > > > vfs_get_tree+0x88/0x270 fs/super.c:1489 > > > > do_new_mount+0x289/0xad0 fs/namespace.c:3145 > > > > do_mount fs/namespace.c:3488 [inline] > > > > __do_sys_mount fs/namespace.c:3697 [inline] > > > > __se_sys_mount+0x2d3/0x3c0 fs/namespace.c:3674 > > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > > > do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 > > > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > RIP: 0033:0x7f89fa3f4aca > > > > Code: 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > > > > RSP: 002b:00007fffd5fb5ef8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 > > > > RAX: ffffffffffffffda RBX: 00646975756f6e2c RCX: 00007f89fa3f4aca > > > > RDX: 0000000020000100 RSI: 0000000020009640 RDI: 00007fffd5fb5f10 > > > > RBP: 00007fffd5fb5f10 R08: 00007fffd5fb5f50 R09: 000000000000970d > > > > R10: 0000000000200800 R11: 0000000000000206 R12: 0000000000000004 > > > > R13: 0000555556c6b2c0 R14: 0000000000200800 R15: 00007fffd5fb5f50 > > > > > > > > > > > > The fuzzed image contains an AGF with an obviously garbage > > > > agf_refcount_level value of 32, and a dirty log with a buffer log item > > > > for that AGF. The ondisk AGF has a higher LSN than the recovered log > > > > item. xlog_recover_buf_commit_pass2 reads the buffer, compares the > > > > LSNs, and decides to skip replay because the ondisk buffer appears to be > > > > newer. > > > > > > > > Unfortunately, the ondisk buffer is corrupt, but recovery just read the > > > > buffer with no buffer ops specified: > > > > > > > > error = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, > > > > buf_f->blf_len, buf_flags, &bp, NULL); > > > > > > > > Skipping the buffer leaves its contents in memory unverified. This sets > > > > us up for a kernel crash because xfs_refcount_recover_cow_leftovers > > > > reads the buffer (which is still around in XBF_DONE state, so no read > > > > verification) and creates a refcountbt cursor of height 32. This is > > > > impossible so we run off the end of the cursor object and crash. > > > > > > > > Fix this by invoking the verifier on all skipped buffers and aborting > > > > log recovery if the ondisk buffer is corrupt. It might be smarter to > > > > force replay the log item atop the buffer and then see if it'll pass the > > > > write verifier (like ext4 does) but for now let's go with the > > > > conservative option where we stop immediately. > > > > > > > > Link: https://syzkaller.appspot.com/bug?extid=7e9494b8b399902e994e > > > > Fixes: 67dc288c2106 ("xfs: ensure verifiers are attached to recovered buffers") > > > > Signed-off-by: Darrick J. Wong > > > > --- > > > > fs/xfs/xfs_buf_item_recover.c | 10 ++++++++++ > > > > 1 file changed, 10 insertions(+) > > > > > > Rightly or wrongly, CVE-2023-212 has been raised against this issue. > > > > > > It looks as though the Fixes: tag above was stripped when applied. > > > > > > Should this still be submitted to Stable? > > > > Yes, but we have not been successful in persuading any company to pick > > up stable backporting and QA for any kernel newer than 5.15. > > > > All right. I tested this one on 6.1.31. No regressions observed. > > Darrick, > > I know you literally said Yes to stable above, > but please state your official ACK and I will send it to stable 6.1.y > so that we can follow up with the rest of the LTS Acked-by: Darrick J. Wong --D > > Thanks, > Amir.