[PATCH AUTOSEL 5.8 72/72] block: don't do revalidate zones on invalid devices

Sasha Levin
2020-08-08T23:48:49Z

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