• Johannes Thumshirn's avatar
    block: don't do revalidate zones on invalid devices · 1a1206dc
    Johannes Thumshirn authored
    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: 6c6b3549 ("block: set the zone size in blk_revalidate_disk_zones atomically")
    Signed-off-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
    Reviewed-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    1a1206dc
blk-zoned.c 14 KB