1a1206dc4c
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.