Re: [PATCH 1/1] Revert "iomap: fall back to buffered writes for invalidation failures"

[Damien Le Moal]

On 2022/02/09 17:52, Lee Jones wrote:
> This reverts commit 60263d5889e6dc5987dc51b801be4955ff2e4aa7.
> 
> Reverting since this commit opens a potential avenue for abuse.
> 
> The C-reproducer and more information can be found at the link below.
> 
> With this patch applied, I can no longer get the repro to trigger.
> 
>   kernel BUG at fs/ext4/inode.c:2647!
>   invalid opcode: 0000 [#1] PREEMPT SMP KASAN
>   CPU: 0 PID: 459 Comm: syz-executor359 Tainted: G        W         5.10.93-syzkaller-01028-g0347b1658399 #0
>   Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>   RIP: 0010:mpage_prepare_extent_to_map+0xbe9/0xc00 fs/ext4/inode.c:2647
>   Code: e8 fc bd c3 ff e9 80 f6 ff ff 44 89 e9 80 e1 07 38 c1 0f 8c a6 fe ff ff 4c 89 ef e8 e1 bd c3 ff e9 99 fe ff ff e8 87 c9 89 ff <0f> 0b e8 80 c9 89 ff 0f 0b e8 79 1e b8 02 66 0f 1f 84 00 00 00 00
>   RSP: 0018:ffffc90000e2e9c0 EFLAGS: 00010293
>   RAX: ffffffff81e321f9 RBX: 0000000000000000 RCX: ffff88810c12cf00
>   RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
>   RBP: ffffc90000e2eb90 R08: ffffffff81e31e71 R09: fffff940008d68b1
>   R10: fffff940008d68b1 R11: 0000000000000000 R12: ffffea00046b4580
>   R13: ffffc90000e2ea80 R14: 000000000000011e R15: dffffc0000000000
>   FS:  00007fcfd0717700(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00007fcfd07d5520 CR3: 000000010a142000 CR4: 00000000003506b0
>   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>   Call Trace:
>    ext4_writepages+0xcbb/0x3950 fs/ext4/inode.c:2776
>    do_writepages+0x13a/0x280 mm/page-writeback.c:2358
>    __filemap_fdatawrite_range+0x356/0x420 mm/filemap.c:427
>    filemap_write_and_wait_range+0x64/0xe0 mm/filemap.c:660
>    __iomap_dio_rw+0x621/0x10c0 fs/iomap/direct-io.c:495
>    iomap_dio_rw+0x35/0x80 fs/iomap/direct-io.c:611
>    ext4_dio_write_iter fs/ext4/file.c:571 [inline]
>    ext4_file_write_iter+0xfc5/0x1b70 fs/ext4/file.c:681
>    do_iter_readv_writev+0x548/0x740 include/linux/fs.h:1941
>    do_iter_write+0x182/0x660 fs/read_write.c:866
>    vfs_iter_write+0x7c/0xa0 fs/read_write.c:907
>    iter_file_splice_write+0x7fb/0xf70 fs/splice.c:686
>    do_splice_from fs/splice.c:764 [inline]
>    direct_splice_actor+0xfe/0x130 fs/splice.c:933
>    splice_direct_to_actor+0x4f4/0xbc0 fs/splice.c:888
>    do_splice_direct+0x28b/0x3e0 fs/splice.c:976
>    do_sendfile+0x914/0x1390 fs/read_write.c:1257
> 
> Link: https://syzkaller.appspot.com/bug?extid=41c966bf0729a530bd8d
> 
> From the patch:
> Cc: Stable <stable@xxxxxxxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Dave Chinner <dchinner@xxxxxxxxxx>
> Cc: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
> Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Cc: Bob Peterson <rpeterso@xxxxxxxxxx>
> Cc: Damien Le Moal <damien.lemoal@xxxxxxx>
> Cc: Theodore Ts'o <tytso@xxxxxxx> # for ext4
> Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> Cc: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
> 
> Others:
> Cc: Johannes Thumshirn <jth@xxxxxxxxxx>
> Cc: linux-xfs@xxxxxxxxxxxxxxx
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Cc: linux-ext4@xxxxxxxxxxxxxxx
> Cc: cluster-devel@xxxxxxxxxx
> 
> Fixes: 60263d5889e6d ("iomap: fall back to buffered writes for invalidation failures")
> Reported-by: syzbot+0ed9f769264276638893@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>

For zonefs:

Acked-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>



-- 
Damien Le Moal
Western Digital Research