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commit 866d65745b635927c3d1343ab67e6fd4a99d116d upstream.
The write pointer of zones that are in the full condition is always
invalid. Reflect that fact by setting the write pointer of full zones
to ULLONG_MAX.
Fixes: eb0570c7df23 ("block: new zoned loop block device driver")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit cf28f6f923cb1dd2765b5c3d7697bb4dcf2096a0 upstream.
zloop_rw() will fail any regular write operation that targets a full
sequential zone. The check for this is indirect and achieved by checking
the write pointer alignment of the write operation. But this check is
ineffective for zone append operations since these are alwasy
automatically directed at a zone write pointer.
Prevent zone append operations from being executed in a full zone with
an explicit check of the zone condition.
Fixes: eb0570c7df23 ("block: new zoned loop block device driver")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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When a zoned loop device, or zloop device, is removed, KASAN enabled
kernel reports "BUG KASAN use-after-free" in blk_mq_free_tag_set(). The
BUG happens because zloop_ctl_remove() calls put_disk(), which invokes
zloop_free_disk(). The zloop_free_disk() frees the memory allocated for
the zlo pointer. However, after the memory is freed, zloop_ctl_remove()
calls blk_mq_free_tag_set(&zlo->tag_set), which accesses the freed zlo.
Hence the KASAN use-after-free.
zloop_ctl_remove()
put_disk(zlo->disk)
put_device()
kobject_put()
...
zloop_free_disk()
kvfree(zlo)
blk_mq_free_tag_set(&zlo->tag_set)
To avoid the BUG, move the call to blk_mq_free_tag_set(&zlo->tag_set)
from zloop_ctl_remove() into zloop_free_disk(). This ensures that
the tag_set is freed before the call to kvfree(zlo).
Fixes: eb0570c7df23 ("block: new zoned loop block device driver")
CC: stable@vger.kernel.org
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250731110745.165751-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The zoned loop block device driver allows a user to create emulated
zoned block devices using one regular file per zone as backing storage.
Compared to null_blk or scsi_debug, it has the advantage of allowing
emulating large zoned devices without requiring the same amount of
memory as the capacity of the emulated device. Furthermore, zoned
devices emulated with this driver can be re-started after a host reboot
without any loss of the state of the device zones, which is something
that null_blk and scsi_debug do not support.
This initial implementation is simple and does not support zone resource
limits. That is, a zoned loop block device limits for the maximum number
of open zones and maximum number of active zones is always 0.
This driver can be either compiled in-kernel or as a module, named
"zloop". Compilation of this driver depends on the block layer support
for zoned block device (CONFIG_BLK_DEV_ZONED must be set).
Using the zloop driver to create and delete zoned block devices is
done by writing commands to the zoned loop control character device file
(/dev/zloop-control). Creating a device is done with:
$ echo "add [options]" > /dev/zloop-control
The options available for the "add" operation cat be listed by reading
the zloop-control device file:
$ cat /dev/zloop-control
add id=%d,capacity_mb=%u,zone_size_mb=%u,zone_capacity_mb=%u,conv_zones=%u,base_dir=%s,nr_queues=%u,queue_depth=%u
remove id=%d
The options available allow controlling the zoned device total
capacity, zone size, zone capactity of sequential zones, total number
of conventional zones, base directory for the zones backing file, number
of I/O queues and the maximum queue depth of I/O queues.
Deleting a device is done using the "remove" command:
$ echo "remove id=0" > /dev/zloop-control
This implementation passes various tests using zonefs and fio (t/zbd
tests) and provides a state machine for zone conditions that is
compliant with the T10 ZBC and NVMe ZNS specifications.
Co-developed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250407075222.170336-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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