From: Qu Wenruo <wqu@suse.com>
To: linux-btrfs@vger.kernel.org
Cc: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Subject: [PATCH 2/3] btrfs: relocation: Fix KASAN report on create_reloc_tree due to extended reloc tree lifepsan
Date: Wed, 11 Dec 2019 13:00:03 +0800 [thread overview]
Message-ID: <20191211050004.18414-3-wqu@suse.com> (raw)
In-Reply-To: <20191211050004.18414-1-wqu@suse.com>
[BUG]
When running workload with balance start/cancel, snapshot
creation/deletion and fsstress, we can hit the following KASAN report:
==================================================================
BUG: KASAN: use-after-free in create_reloc_root+0x9f/0x460 [btrfs]
Read of size 8 at addr ffff8881571741f0 by task btrfs/3539
CPU: 6 PID: 3539 Comm: btrfs Tainted: G O 5.5.0-rc1-custom+ #40
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
dump_stack+0xc2/0x11a
print_address_description.constprop.0+0x20/0x210
__kasan_report.cold+0x1b/0x41
kasan_report+0x12/0x20
__asan_load8+0x54/0x90
create_reloc_root+0x9f/0x460 [btrfs]
btrfs_reloc_post_snapshot+0xff/0x6c0 [btrfs]
create_pending_snapshot+0xa9b/0x15f0 [btrfs]
create_pending_snapshots+0x111/0x140 [btrfs]
btrfs_commit_transaction+0x7a6/0x1360 [btrfs]
btrfs_mksubvol+0x915/0x960 [btrfs]
btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs]
btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs]
btrfs_ioctl+0x241b/0x3e60 [btrfs]
do_vfs_ioctl+0x831/0xb10
ksys_ioctl+0x67/0x90
__x64_sys_ioctl+0x43/0x50
do_syscall_64+0x79/0xe0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
[CAUSE]
This is another case where root->reloc_root is accessed without checking
if the reloc root is already dead.
[FIX]
Also check DEAD_RELOC_TREE bit before accessing root->reloc_root.
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots")
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/relocation.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index bb41b981e493..619ccb183515 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4755,7 +4755,14 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
struct reloc_control *rc = root->fs_info->reloc_ctl;
int ret;
- if (!root->reloc_root || !rc)
+ /*
+ * We don't need to use reloc tree if:
+ * - No reloc tree
+ * - Relocation not running
+ * - Reloc tree already merged
+ */
+ if (!root->reloc_root || !rc || test_bit(BTRFS_ROOT_DEAD_RELOC_TREE,
+ &root->state))
return 0;
rc = root->fs_info->reloc_ctl;
--
2.24.0
next prev parent reply other threads:[~2019-12-11 5:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-11 5:00 [PATCH 0/3] btrfs: fixes for relocation to avoid KASAN reports Qu Wenruo
2019-12-11 5:00 ` [PATCH 1/3] btrfs: relocation: Fix a KASAN use-after-free bug due to extended reloc tree lifespan Qu Wenruo
2019-12-11 14:53 ` Josef Bacik
2019-12-11 5:00 ` Qu Wenruo [this message]
2019-12-11 14:55 ` [PATCH 2/3] btrfs: relocation: Fix KASAN report on create_reloc_tree due to extended reloc tree lifepsan Josef Bacik
2019-12-11 15:15 ` David Sterba
2019-12-11 5:00 ` [PATCH 3/3] btrfs: relocation: Fix a KASAN report on btrfs_reloc_pre_snapshot() due to extended reloc root lifespan Qu Wenruo
2019-12-11 14:55 ` Josef Bacik
2019-12-11 15:34 ` [PATCH 0/3] btrfs: fixes for relocation to avoid KASAN reports David Sterba
2019-12-12 0:39 ` Qu Wenruo
2019-12-12 14:28 ` David Sterba
2020-01-03 15:52 ` David Sterba
2020-01-03 16:15 ` David Sterba
2020-01-04 9:37 ` Qu Wenruo
2020-01-04 13:18 ` Qu Wenruo
2020-01-06 7:04 ` Qu Wenruo
2020-01-06 18:23 ` David Sterba
2020-01-04 1:32 ` Qu Wenruo
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