From: Josef Bacik <josef@toxicpanda.com>
To: Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs: Don't submit any btree write bio after transaction is aborted
Date: Mon, 3 Feb 2020 11:38:34 -0500 [thread overview]
Message-ID: <4587d936-07c6-1319-22a1-ceb8dd7cbeff@toxicpanda.com> (raw)
In-Reply-To: <20200203064558.27064-1-wqu@suse.com>
On 2/3/20 1:45 AM, Qu Wenruo wrote:
> [BUG]
> There is a fuzzed image which could cause KASAN report at unmount time.
>
> ==================================================================
> BUG: KASAN: use-after-free in btrfs_queue_work+0x2c1/0x390
> Read of size 8 at addr ffff888067cf6848 by task umount/1922
>
> CPU: 0 PID: 1922 Comm: umount Tainted: G W 5.0.21 #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
> Call Trace:
> dump_stack+0x5b/0x8b
> print_address_description+0x70/0x280
> kasan_report+0x13a/0x19b
> btrfs_queue_work+0x2c1/0x390
> btrfs_wq_submit_bio+0x1cd/0x240
> btree_submit_bio_hook+0x18c/0x2a0
> submit_one_bio+0x1be/0x320
> flush_write_bio.isra.41+0x2c/0x70
> btree_write_cache_pages+0x3bb/0x7f0
> do_writepages+0x5c/0x130
> __writeback_single_inode+0xa3/0x9a0
> writeback_single_inode+0x23d/0x390
> write_inode_now+0x1b5/0x280
> iput+0x2ef/0x600
> close_ctree+0x341/0x750
> generic_shutdown_super+0x126/0x370
> kill_anon_super+0x31/0x50
> btrfs_kill_super+0x36/0x2b0
> deactivate_locked_super+0x80/0xc0
> deactivate_super+0x13c/0x150
> cleanup_mnt+0x9a/0x130
> task_work_run+0x11a/0x1b0
> exit_to_usermode_loop+0x107/0x130
> do_syscall_64+0x1e5/0x280
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> [CAUSE]
> The fuzzed image has a corrupted extent tree, which can pass
> tree-checker but run_delayed_refs() will still detect such bad extent
> tree, and abort transaction.
>
> The problem happens at unmount time, where btrfs will stop all workers
> first, then call iput() on the btree inode.
>
> Since btree inode still has some dirty pages, iput() will try to write
> back such dirty pages, but all related work queues are already freed,
> triggering use-after-free bug.
>
This sounds like our abort isn't doing the right thing? We should be cleaning
all dirty pages at this point so nothing gets submitted after the fact. Thanks,
Josef
next prev parent reply other threads:[~2020-02-03 16:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-03 6:45 [PATCH] btrfs: Don't submit any btree write bio after transaction is aborted Qu Wenruo
2020-02-03 16:38 ` Josef Bacik [this message]
2020-02-04 5:00 ` Qu Wenruo
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