From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: "zhangyi (F)" <yi.zhang@huawei.com>
Cc: linux-ext4@vger.kernel.org, jack@suse.com, adilger.kernel@dilger.ca
Subject: Re: [PATCH v2 1/7] ext4: clear buffer verified flag if read meta block from disk
Date: Thu, 8 Oct 2020 21:41:40 -0400 [thread overview]
Message-ID: <20201009014140.GA816148@mit.edu> (raw)
In-Reply-To: <20200924073337.861472-2-yi.zhang@huawei.com>
On Thu, Sep 24, 2020 at 03:33:31PM +0800, zhangyi (F) wrote:
> The metadata buffer is no longer trusted after we read it from disk
> again because it is not uptodate for some reasons (e.g. failed to write
> back). Otherwise we may get below memory corruption problem in
> ext4_ext_split()->memset() if we read stale data from the newly
> allocated extent block on disk which has been failed to async write
> out but miss verify again since the verified bit has already been set
> on the buffer.
>
> [ 29.774674] BUG: unable to handle kernel paging request at ffff88841949d000
> ...
> [ 29.783317] Oops: 0002 [#2] SMP
> [ 29.784219] R10: 00000000000f4240 R11: 0000000000002e28 R12: ffff88842fa1c800
> [ 29.784627] CPU: 1 PID: 126 Comm: kworker/u4:3 Tainted: G D W
> [ 29.785546] R13: ffffffff9cddcc20 R14: ffffffff9cddd420 R15: ffff88842fa1c2f8
> [ 29.786679] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),BIOS ?-20190727_0738364
> [ 29.787588] FS: 0000000000000000(0000) GS:ffff88842fa00000(0000) knlGS:0000000000000000
> [ 29.789288] Workqueue: writeback wb_workfn
> [ 29.790319] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 29.790321] (flush-8:0)
> [ 29.790844] CR2: 0000000000000008 CR3: 00000004234f2000 CR4: 00000000000006f0
> [ 29.791924] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 29.792839] RIP: 0010:__memset+0x24/0x30
> [ 29.793739] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 29.794256] Code: 90 90 90 90 90 90 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 033
> [ 29.795161] Kernel panic - not syncing: Fatal exception in interrupt
> ...
> [ 29.808149] Call Trace:
> [ 29.808475] ext4_ext_insert_extent+0x102e/0x1be0
> [ 29.809085] ext4_ext_map_blocks+0xa89/0x1bb0
> [ 29.809652] ext4_map_blocks+0x290/0x8a0
> [ 29.809085] ext4_ext_map_blocks+0xa89/0x1bb0
> [ 29.809652] ext4_map_blocks+0x290/0x8a0
> [ 29.810161] ext4_writepages+0xc85/0x17c0
> ...
>
> Fix this by clearing buffer's verified bit if we read meta block from
> disk again.
>
> Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
> Cc: stable@vger.kernel.org
Thanks, applied.
- Ted
next prev parent reply other threads:[~2020-10-09 1:42 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 7:33 [PATCH v2 0/7] ext4: fix a memory corrupt problem zhangyi (F)
2020-09-24 7:33 ` [PATCH v2 1/7] ext4: clear buffer verified flag if read meta block from disk zhangyi (F)
2020-10-09 1:41 ` Theodore Y. Ts'o [this message]
2020-09-24 7:33 ` [PATCH v2 2/7] ext4: introduce new metadata buffer read helpers zhangyi (F)
2020-10-09 1:43 ` Theodore Y. Ts'o
2020-09-24 7:33 ` [PATCH v2 3/7] ext4: use common helpers in all places reading metadata buffers zhangyi (F)
2020-10-09 1:48 ` Theodore Y. Ts'o
2020-09-24 7:33 ` [PATCH v2 4/7] ext4: use ext4_buffer_uptodate() in __ext4_get_inode_loc() zhangyi (F)
2020-10-09 1:49 ` Theodore Y. Ts'o
2020-09-24 7:33 ` [PATCH v2 5/7] ext4: introduce ext4_sb_breadahead_unmovable() to replace sb_breadahead_unmovable() zhangyi (F)
2020-10-09 1:55 ` Theodore Y. Ts'o
2020-09-24 7:33 ` [PATCH v2 6/7] ext4: use ext4_sb_bread() instead of sb_bread() zhangyi (F)
2020-10-09 1:57 ` Theodore Y. Ts'o
2020-09-24 7:33 ` [PATCH v2 7/7] ext4: introduce ext4_sb_bread_unmovable() to replace sb_bread_unmovable() zhangyi (F)
2020-10-09 2:00 ` Theodore Y. Ts'o
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