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 89803C7EE45 for ; Mon, 12 Jun 2023 10:45:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234126AbjFLKpL (ORCPT ); Mon, 12 Jun 2023 06:45:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234901AbjFLKod (ORCPT ); Mon, 12 Jun 2023 06:44:33 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76CFB55BA for ; Mon, 12 Jun 2023 03:29:23 -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 131B561372 for ; Mon, 12 Jun 2023 10:29:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2342AC433EF; Mon, 12 Jun 2023 10:29:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686565762; bh=Dlp7GNrWuB6drP4QziRSb9t+AHQdPPdDFWKqmSCyeRI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GCgrDYyMOitesdZFx0WQka6qDVBIXEVDYzle8HsLODfM9QD22rA2ojEDcB7HVFqj4 pK2+xU2SZ59kI5eE1rCThdsy9Htn+KzPVcTpVmPmzY4RlusfwB+8EGjOO+P+i4DvqV GS3hP6keWuNdakDVnGdClSyVv+bgG+y7HM4VMBu0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, TOTE Robot , Sweet Tea Dorminy , Nikolay Borisov , Zixuan Fu , David Sterba , Stefan Ghinea Subject: [PATCH 4.14 20/21] btrfs: unset reloc control if transaction commit fails in prepare_to_relocate() Date: Mon, 12 Jun 2023 12:26:15 +0200 Message-ID: <20230612101651.733633951@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230612101651.048240731@linuxfoundation.org> References: <20230612101651.048240731@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Zixuan Fu commit 85f02d6c856b9f3a0acf5219de6e32f58b9778eb upstream. In btrfs_relocate_block_group(), the rc is allocated. Then btrfs_relocate_block_group() calls relocate_block_group() prepare_to_relocate() set_reloc_control() that assigns rc to the variable fs_info->reloc_ctl. When prepare_to_relocate() returns, it calls btrfs_commit_transaction() btrfs_start_dirty_block_groups() btrfs_alloc_path() kmem_cache_zalloc() which may fail for example (or other errors could happen). When the failure occurs, btrfs_relocate_block_group() detects the error and frees rc and doesn't set fs_info->reloc_ctl to NULL. After that, in btrfs_init_reloc_root(), rc is retrieved from fs_info->reloc_ctl and then used, which may cause a use-after-free bug. This possible bug can be triggered by calling btrfs_ioctl_balance() before calling btrfs_ioctl_defrag(). To fix this possible bug, in prepare_to_relocate(), check if btrfs_commit_transaction() fails. If the failure occurs, unset_reloc_control() is called to set fs_info->reloc_ctl to NULL. The error log in our fault-injection testing is shown as follows: [ 58.751070] BUG: KASAN: use-after-free in btrfs_init_reloc_root+0x7ca/0x920 [btrfs] ... [ 58.753577] Call Trace: ... [ 58.755800] kasan_report+0x45/0x60 [ 58.756066] btrfs_init_reloc_root+0x7ca/0x920 [btrfs] [ 58.757304] record_root_in_trans+0x792/0xa10 [btrfs] [ 58.757748] btrfs_record_root_in_trans+0x463/0x4f0 [btrfs] [ 58.758231] start_transaction+0x896/0x2950 [btrfs] [ 58.758661] btrfs_defrag_root+0x250/0xc00 [btrfs] [ 58.759083] btrfs_ioctl_defrag+0x467/0xa00 [btrfs] [ 58.759513] btrfs_ioctl+0x3c95/0x114e0 [btrfs] ... [ 58.768510] Allocated by task 23683: [ 58.768777] ____kasan_kmalloc+0xb5/0xf0 [ 58.769069] __kmalloc+0x227/0x3d0 [ 58.769325] alloc_reloc_control+0x10a/0x3d0 [btrfs] [ 58.769755] btrfs_relocate_block_group+0x7aa/0x1e20 [btrfs] [ 58.770228] btrfs_relocate_chunk+0xf1/0x760 [btrfs] [ 58.770655] __btrfs_balance+0x1326/0x1f10 [btrfs] [ 58.771071] btrfs_balance+0x3150/0x3d30 [btrfs] [ 58.771472] btrfs_ioctl_balance+0xd84/0x1410 [btrfs] [ 58.771902] btrfs_ioctl+0x4caa/0x114e0 [btrfs] ... [ 58.773337] Freed by task 23683: ... [ 58.774815] kfree+0xda/0x2b0 [ 58.775038] free_reloc_control+0x1d6/0x220 [btrfs] [ 58.775465] btrfs_relocate_block_group+0x115c/0x1e20 [btrfs] [ 58.775944] btrfs_relocate_chunk+0xf1/0x760 [btrfs] [ 58.776369] __btrfs_balance+0x1326/0x1f10 [btrfs] [ 58.776784] btrfs_balance+0x3150/0x3d30 [btrfs] [ 58.777185] btrfs_ioctl_balance+0xd84/0x1410 [btrfs] [ 58.777621] btrfs_ioctl+0x4caa/0x114e0 [btrfs] ... Reported-by: TOTE Robot CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Sweet Tea Dorminy Reviewed-by: Nikolay Borisov Signed-off-by: Zixuan Fu Signed-off-by: David Sterba Signed-off-by: Stefan Ghinea Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/relocation.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4014,7 +4014,12 @@ int prepare_to_relocate(struct reloc_con */ return PTR_ERR(trans); } - return btrfs_commit_transaction(trans); + + ret = btrfs_commit_transaction(trans); + if (ret) + unset_reloc_control(rc); + + return ret; } static noinline_for_stack int relocate_block_group(struct reloc_control *rc)