From patchwork Mon Jul 13 14:11:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 11659837 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ABD6613B6 for ; Mon, 13 Jul 2020 14:12:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D99C20738 for ; Mon, 13 Jul 2020 14:12:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594649531; bh=PjxtX/bHRhHUlUrSOtrwxCzHnXc+ZQ1QbzavBXsSdD8=; h=From:To:Subject:Date:List-ID:From; b=S726UJcen+a7i/nIEtRSdZ78Q/SXn7nrFD11hQV9o1htCRCsCaYlq1Jgo8U9F1+pp Q4PGQ9I7l2q8U4L7OltViCN37W4PyQpYeF1XTjZmCgy7qI969K4lyJTVRo23AQ1fW6 rvG7hyWcG2CT9EzlxZOAW//9Q21h2/Df3pUDy31M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729792AbgGMOMK (ORCPT ); Mon, 13 Jul 2020 10:12:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:38814 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729681AbgGMOMK (ORCPT ); Mon, 13 Jul 2020 10:12:10 -0400 Received: from debian8.Home (bl8-197-74.dsl.telepac.pt [85.241.197.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2562120738 for ; Mon, 13 Jul 2020 14:12:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594649529; bh=PjxtX/bHRhHUlUrSOtrwxCzHnXc+ZQ1QbzavBXsSdD8=; h=From:To:Subject:Date:From; b=oKCCrMuPp0mWNlXTIRDSkbiiCLTRv86wVYsGHMgJ14nMSwuBkWDQ9acu86cpdLCFT 2UZhyfG+Fig2sr17IZ9txUobjQ+Fs4OsX+8k1JUZ+oNfbQA7xZsoGkqKuVrytQcD5n 2z+qGYPKUUI4aZbCpA9LXRhai7IKKgvAdp74mvj0= From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH] btrfs: fix double free on ulist after backref resolution failure Date: Mon, 13 Jul 2020 15:11:56 +0100 Message-Id: <20200713141156.1772789-1-fdmanana@kernel.org> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Filipe Manana At btrfs_find_all_roots_safe() we allocate a ulist and set the **roots argument to point to it. However if later we fail due to an error returned by find_parent_nodes(), we free that ulist but leave a dangling pointer in the **roots argument. Upon receiving the error, a caller of this function can attempt to free the same ulist again, resulting in an invalid memory access. One such scenario is during qgroup accounting: btrfs_qgroup_account_extents() --> calls btrfs_find_all_roots() passes &new_roots (a stack allocated pointer) to btrfs_find_all_roots() --> btrfs_find_all_roots() just calls btrfs_find_all_roots_safe() passing &new_roots to it --> allocates ulist and assigns its address to **roots (which points to new_roots from btrfs_qgroup_account_extents()) --> find_parent_nodes() returns an error, so we free the ulist and leave **roots pointing to it after returning --> btrfs_qgroup_account_extents() sees btrfs_find_all_roots() returned an error and jumps to the label 'cleanup', which just tries to free again the same ulist Stack trace example: ------------[ cut here ]------------ BTRFS: tree first key check failed WARNING: CPU: 1 PID: 1763215 at fs/btrfs/disk-io.c:422 btrfs_verify_level_key+0xe0/0x180 [btrfs] Modules linked in: dm_snapshot dm_thin_pool (...) CPU: 1 PID: 1763215 Comm: fsstress Tainted: G W 5.8.0-rc3-btrfs-next-64 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:btrfs_verify_level_key+0xe0/0x180 [btrfs] Code: 28 5b 5d (...) RSP: 0018:ffffb89b473779a0 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff90397759bf08 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000027 RDI: 00000000ffffffff RBP: ffff9039a419c000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffffb89b43301000 R12: 000000000000005e R13: ffffb89b47377a2e R14: ffffb89b473779af R15: 0000000000000000 FS: 00007fc47e1e1000(0000) GS:ffff9039ac200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc47e1df000 CR3: 00000003d9e4e001 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: read_block_for_search+0xf6/0x350 [btrfs] btrfs_next_old_leaf+0x242/0x650 [btrfs] resolve_indirect_refs+0x7cf/0x9e0 [btrfs] find_parent_nodes+0x4ea/0x12c0 [btrfs] btrfs_find_all_roots_safe+0xbf/0x130 [btrfs] btrfs_qgroup_account_extents+0x9d/0x390 [btrfs] btrfs_commit_transaction+0x4f7/0xb20 [btrfs] btrfs_sync_file+0x3d4/0x4d0 [btrfs] do_fsync+0x38/0x70 __x64_sys_fdatasync+0x13/0x20 do_syscall_64+0x5c/0xe0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fc47e2d72e3 Code: Bad RIP value. RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3 RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003 RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8 R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50 irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] 0x0 hardirqs last disabled at (0): [] copy_process+0x755/0x1eb0 softirqs last enabled at (0): [] copy_process+0x755/0x1eb0 softirqs last disabled at (0): [<0000000000000000>] 0x0 ---[ end trace 8639237550317b48 ]--- BTRFS error (device sdc): tree first key mismatch detected, bytenr=62324736 parent_transid=94 key expected=(262,108,1351680) has=(259,108,1921024) general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI CPU: 2 PID: 1763215 Comm: fsstress Tainted: G W 5.8.0-rc3-btrfs-next-64 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:ulist_release+0x14/0x60 [btrfs] Code: c7 07 00 (...) RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282 RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840 RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840 R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840 FS: 00007fc47e1e1000(0000) GS:ffff9039ac600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8c1c0a51c8 CR3: 00000003d9e4e004 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ulist_free+0x13/0x20 [btrfs] btrfs_qgroup_account_extents+0xf3/0x390 [btrfs] btrfs_commit_transaction+0x4f7/0xb20 [btrfs] btrfs_sync_file+0x3d4/0x4d0 [btrfs] do_fsync+0x38/0x70 __x64_sys_fdatasync+0x13/0x20 do_syscall_64+0x5c/0xe0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fc47e2d72e3 Code: Bad RIP value. RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3 RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003 RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8 R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50 Modules linked in: dm_snapshot dm_thin_pool (...) ---[ end trace 8639237550317b49 ]--- RIP: 0010:ulist_release+0x14/0x60 [btrfs] Code: c7 07 00 (...) RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282 RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840 RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840 R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840 FS: 00007fc47e1e1000(0000) GS:ffff9039ad200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6a776f7d40 CR3: 00000003d9e4e002 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Fix this by making btrfs_find_all_roots_safe() set *roots to NULL after it frees the ulist. Fixes: 8da6d5815c592b ("Btrfs: added btrfs_find_all_roots()") Signed-off-by: Filipe Manana Reviewed-by: Josef Bacik --- fs/btrfs/backref.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index d888e71e66b6..ea10f7bc99ab 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -1461,6 +1461,7 @@ static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans, if (ret < 0 && ret != -ENOENT) { ulist_free(tmp); ulist_free(*roots); + *roots = NULL; return ret; } node = ulist_next(tmp, &uiter);