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    Subject[PATCH AUTOSEL 5.8 72/72] block: don't do revalidate zones on invalid devices
    Date
    From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

    [ Upstream commit 1a1206dc4cf02cee4b5cbce583ee4c22368b4c28 ]

    When we loose a device for whatever reason while (re)scanning zones, we
    trip over a NULL pointer in blk_revalidate_zone_cb, like in the following
    log:

    sd 0:0:0:0: [sda] 3418095616 4096-byte logical blocks: (14.0 TB/12.7 TiB)
    sd 0:0:0:0: [sda] 52156 zones of 65536 logical blocks
    sd 0:0:0:0: [sda] Write Protect is off
    sd 0:0:0:0: [sda] Mode Sense: 37 00 00 08
    sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
    sd 0:0:0:0: [sda] REPORT ZONES start lba 1065287680 failed
    sd 0:0:0:0: [sda] REPORT ZONES: Result: hostbyte=0x00 driverbyte=0x08
    sd 0:0:0:0: [sda] Sense Key : 0xb [current]
    sd 0:0:0:0: [sda] ASC=0x0 ASCQ=0x6
    sda: failed to revalidate zones
    sd 0:0:0:0: [sda] 0 4096-byte logical blocks: (0 B/0 B)
    sda: detected capacity change from 14000519643136 to 0
    ==================================================================
    BUG: KASAN: null-ptr-deref in blk_revalidate_zone_cb+0x1b7/0x550
    Write of size 8 at addr 0000000000000010 by task kworker/u4:1/58

    CPU: 1 PID: 58 Comm: kworker/u4:1 Not tainted 5.8.0-rc1 #692
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4-rebuilt.opensuse.org 04/01/2014
    Workqueue: events_unbound async_run_entry_fn
    Call Trace:
    dump_stack+0x7d/0xb0
    ? blk_revalidate_zone_cb+0x1b7/0x550
    kasan_report.cold+0x5/0x37
    ? blk_revalidate_zone_cb+0x1b7/0x550
    check_memory_region+0x145/0x1a0
    blk_revalidate_zone_cb+0x1b7/0x550
    sd_zbc_parse_report+0x1f1/0x370
    ? blk_req_zone_write_trylock+0x200/0x200
    ? sectors_to_logical+0x60/0x60
    ? blk_req_zone_write_trylock+0x200/0x200
    ? blk_req_zone_write_trylock+0x200/0x200
    sd_zbc_report_zones+0x3c4/0x5e0
    ? sd_dif_config_host+0x500/0x500
    blk_revalidate_disk_zones+0x231/0x44d
    ? _raw_write_lock_irqsave+0xb0/0xb0
    ? blk_queue_free_zone_bitmaps+0xd0/0xd0
    sd_zbc_read_zones+0x8cf/0x11a0
    sd_revalidate_disk+0x305c/0x64e0
    ? __device_add_disk+0x776/0xf20
    ? read_capacity_16.part.0+0x1080/0x1080
    ? blk_alloc_devt+0x250/0x250
    ? create_object.isra.0+0x595/0xa20
    ? kasan_unpoison_shadow+0x33/0x40
    sd_probe+0x8dc/0xcd2
    really_probe+0x20e/0xaf0
    __driver_attach_async_helper+0x249/0x2d0
    async_run_entry_fn+0xbe/0x560
    process_one_work+0x764/0x1290
    ? _raw_read_unlock_irqrestore+0x30/0x30
    worker_thread+0x598/0x12f0
    ? __kthread_parkme+0xc6/0x1b0
    ? schedule+0xed/0x2c0
    ? process_one_work+0x1290/0x1290
    kthread+0x36b/0x440
    ? kthread_create_worker_on_cpu+0xa0/0xa0
    ret_from_fork+0x22/0x30
    ==================================================================

    When the device is already gone we end up with the following scenario:
    The device's capacity is 0 and thus the number of zones will be 0 as well. When
    allocating the bitmap for the conventional zones, we then trip over a NULL
    pointer.

    So if we encounter a zoned block device with a 0 capacity, don't dare to
    revalidate the zones sizes.

    Fixes: 6c6b35491422 ("block: set the zone size in blk_revalidate_disk_zones atomically")
    Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
    Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    block/blk-zoned.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/block/blk-zoned.c b/block/blk-zoned.c
    index 23831fa8701d8..480dfff69a00c 100644
    --- a/block/blk-zoned.c
    +++ b/block/blk-zoned.c
    @@ -497,6 +497,9 @@ int blk_revalidate_disk_zones(struct gendisk *disk,
    if (WARN_ON_ONCE(!queue_is_mq(q)))
    return -EIO;

    + if (!get_capacity(disk))
    + return -EIO;
    +
    /*
    * Ensure that all memory allocations in this context are done as if
    * GFP_NOIO was specified.
    --
    2.25.1
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