linux-stable.git/drivers/block, branch v7.2.6 Linux kernel stable tree block: mtip32xx: synchronize ioctls with device removal 2026-09-14T11:40:49+00:00 Hongyan Xu getshell@seu.edu.cn 2026-08-06T06:04:41+00:00 b389dc35a55713ac24a145741e76196fea1663bc [ Upstream commit 68940f841d013192086a0f6d7cfbac2cd079e228 ] The ioctl handlers only test REMOVE_PENDING before entering mtip_hw_ioctl(). Removal can set that bit immediately afterwards and free dd->port in mtip_hw_exit() while an ioctl still dereferences it. An already open block device can reach the handlers while del_gendisk() is in progress. Serialize both native and compat ioctls with removal. Set REMOVE_PENDING before taking the mutex so new callers fail after an in-flight ioctl has drained, and hold the mutex until the port has been torn down. Fixes: 88523a61558a ("block: Add driver for Micron RealSSD pcie flash cards") Signed-off-by: Hongyan Xu <getshell@seu.edu.cn> Link: https://patch.msgid.link/20260806060441.676-1-getshell@seu.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 68940f841d013192086a0f6d7cfbac2cd079e228 ]

The ioctl handlers only test REMOVE_PENDING before entering
mtip_hw_ioctl(). Removal can set that bit immediately afterwards and free
dd->port in mtip_hw_exit() while an ioctl still dereferences it. An already
open block device can reach the handlers while del_gendisk() is in
progress.

Serialize both native and compat ioctls with removal. Set REMOVE_PENDING
before taking the mutex so new callers fail after an in-flight ioctl has
drained, and hold the mutex until the port has been torn down.

Fixes: 88523a61558a ("block: Add driver for Micron RealSSD pcie flash cards")
Signed-off-by: Hongyan Xu <getshell@seu.edu.cn>
Link: https://patch.msgid.link/20260806060441.676-1-getshell@seu.edu.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ublk: avoid teardown retry loop on xarray allocation failure 2026-09-14T11:40:49+00:00 Yao Sang sangyao@kylinos.cn 2026-08-04T12:57:36+00:00 b9cc6cc74daf6fef533dbe65d8cee779fea69600 [ Upstream commit 4fd66a7f829f3f38f92a79081f0f2688aed644f0 ] __ublk_shmem_remove_ranges() removes matching maple tree ranges in batches, but first stores each range into a temporary xarray so that the pages can be unpinned after dropping the maple tree lock. That temporary xarray is filled under the maple tree lock with xa_store(..., GFP_ATOMIC). If the store fails before mas_erase(), the current range is left in the tree and the helper returns false. The outer ublk_shmem_remove_ranges() loop then immediately retries the same range. While the atomic allocation keeps failing, the teardown path has no forward progress. The issue can be reproduced with radix_tree_node failslab injection after a SHMEM_ZC buffer has already been registered: # Kernel config: # CONFIG_BLK_DEV_UBLK=y # CONFIG_DEBUG_FS=y # CONFIG_FAULT_INJECTION=y # CONFIG_FAULT_INJECTION_DEBUG_FS=y # CONFIG_FAILSLAB=y echo 10 > /proc/sys/vm/nr_hugepages mkdir -p /tmp/htlb mount -t hugetlbfs none /tmp/htlb fallocate -l 4M /tmp/htlb/ublk_buf dev_id=$(kublk add -t null --shmem_zc \ --htlb /tmp/htlb/ublk_buf | awk -F '[ :]' '/dev id/ {print $3}') echo 1 > /sys/kernel/slab/radix_tree_node/failslab echo Y > /sys/kernel/debug/failslab/cache-filter echo Y > /sys/kernel/debug/failslab/ignore-gfp-wait echo 1 > /sys/kernel/debug/failslab/interval echo -1 > /sys/kernel/debug/failslab/times echo 100 > /sys/kernel/debug/failslab/probability kublk del -n "$dev_id" On the unfixed kernel the delete command was still running after 3 seconds. Disabling failslab made it return. The fault-injection stack showed: should_failslab kmem_cache_alloc_lru_noprof __xas_nomem __xa_store xa_store __ublk_shmem_remove_ranges ublk_cdev_rel ublk_ctrl_del_dev Remove the allocation from the teardown loop. Keep the existing batch limit, but collect {base_pfn, nr_pages} pairs in a fixed-size stack array. Once a matching range is found, the range is erased from the maple tree before dropping the lock, so each successful scan makes progress without depending on any GFP_ATOMIC allocation. With the same failslab settings, the fixed kernel completed "kublk del -n $dev_id" successfully in about 45 ms. Fixes: 309e02dccf64 ("ublk: avoid unpinning pages under maple tree spinlock") Signed-off-by: Yao Sang <sangyao@kylinos.cn> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Link: https://patch.msgid.link/20260804125736.2011774-1-sangyao@kylinos.cn Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4fd66a7f829f3f38f92a79081f0f2688aed644f0 ]

__ublk_shmem_remove_ranges() removes matching maple tree ranges in
batches, but first stores each range into a temporary xarray so that the
pages can be unpinned after dropping the maple tree lock.

That temporary xarray is filled under the maple tree lock with
xa_store(..., GFP_ATOMIC). If the store fails before mas_erase(), the
current range is left in the tree and the helper returns false. The
outer ublk_shmem_remove_ranges() loop then immediately retries the same
range. While the atomic allocation keeps failing, the teardown path has
no forward progress.

The issue can be reproduced with radix_tree_node failslab injection after
a SHMEM_ZC buffer has already been registered:

  # Kernel config:
  #   CONFIG_BLK_DEV_UBLK=y
  #   CONFIG_DEBUG_FS=y
  #   CONFIG_FAULT_INJECTION=y
  #   CONFIG_FAULT_INJECTION_DEBUG_FS=y
  #   CONFIG_FAILSLAB=y

  echo 10 > /proc/sys/vm/nr_hugepages
  mkdir -p /tmp/htlb
  mount -t hugetlbfs none /tmp/htlb
  fallocate -l 4M /tmp/htlb/ublk_buf

  dev_id=$(kublk add -t null --shmem_zc \
		--htlb /tmp/htlb/ublk_buf |
	   awk -F '[ :]' '/dev id/ {print $3}')

  echo 1 > /sys/kernel/slab/radix_tree_node/failslab
  echo Y > /sys/kernel/debug/failslab/cache-filter
  echo Y > /sys/kernel/debug/failslab/ignore-gfp-wait
  echo 1 > /sys/kernel/debug/failslab/interval
  echo -1 > /sys/kernel/debug/failslab/times
  echo 100 > /sys/kernel/debug/failslab/probability

  kublk del -n "$dev_id"

On the unfixed kernel the delete command was still running after 3
seconds. Disabling failslab made it return. The fault-injection stack
showed:

  should_failslab
  kmem_cache_alloc_lru_noprof
  __xas_nomem
  __xa_store
  xa_store
  __ublk_shmem_remove_ranges
  ublk_cdev_rel
  ublk_ctrl_del_dev

Remove the allocation from the teardown loop. Keep the existing batch
limit, but collect {base_pfn, nr_pages} pairs in a fixed-size stack array.
Once a matching range is found, the range is erased from the maple tree
before dropping the lock, so each successful scan makes progress without
depending on any GFP_ATOMIC allocation.

With the same failslab settings, the fixed kernel completed
"kublk del -n $dev_id" successfully in about 45 ms.

Fixes: 309e02dccf64 ("ublk: avoid unpinning pages under maple tree spinlock")
Signed-off-by: Yao Sang <sangyao@kylinos.cn>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260804125736.2011774-1-sangyao@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ublk: reject non-power-of-2 zone sizes in SET_PARAMS 2026-09-14T11:40:49+00:00 Yao Sang sangyao@kylinos.cn 2026-08-14T02:32:24+00:00 6220421b97296ded4af36653b3a1c6faec41a51f [ Upstream commit 2707acf1856da266139986c9398ad722fd4f48c0 ] UBLK_F_ZONED uses params.basic.chunk_sectors as zone size. ublk uses ilog2(chunk_sectors) to get number of zones, so the value must be power of 2. If chunk_sectors is 96 and dev_sectors is 96 * 16, userspace asks for 16 zones. But the shift calculation gets 24 zones. Block layer rejects such zone size when the disk is started. But SET_PARAMS has already returned success, which is confusing for userspace. Reject it in SET_PARAMS with other zoned parameter checks. Fixes: 29802d7ca33b ("ublk: enable zoned storage support") Signed-off-by: Yao Sang <sangyao@kylinos.cn> Link: https://patch.msgid.link/20260814023226.354288-2-sangyao@kylinos.cn Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2707acf1856da266139986c9398ad722fd4f48c0 ]

UBLK_F_ZONED uses params.basic.chunk_sectors as zone size. ublk uses
ilog2(chunk_sectors) to get number of zones, so the value must be power
of 2.

If chunk_sectors is 96 and dev_sectors is 96 * 16, userspace asks for
16 zones. But the shift calculation gets 24 zones.

Block layer rejects such zone size when the disk is started. But
SET_PARAMS has already returned success, which is confusing for
userspace. Reject it in SET_PARAMS with other zoned parameter checks.

Fixes: 29802d7ca33b ("ublk: enable zoned storage support")
Signed-off-by: Yao Sang <sangyao@kylinos.cn>
Link: https://patch.msgid.link/20260814023226.354288-2-sangyao@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
null_blk: serialize configfs attribute updates with device setup 2026-09-14T11:40:48+00:00 Niklas Cassel cassel@kernel.org 2026-08-13T14:14:56+00:00 d3d35dd045a35991bf6fd13de5f293e6dd7bf3b3 [ Upstream commit 4e1f23f9c33c156be7e313b40695af5a3a834739 ] The attribute store methods generated with NULLB_DEVICE_ATTR() refuse to change the configuration of a live device by testing NULLB_DEV_FL_CONFIGURED, but that flag is only set by nullb_device_power_store() after null_add_dev() has returned, and the store methods take no lock at all. configfs only serializes writes to the same open file (buffer->mutex), so a write to any attribute can run concurrently with null_add_dev() and change the device configuration while it is being used. null_add_dev() reads the configuration several times, e.g. dev->zoned is read once to set up the queue limits and once to initialize the zone resources: CPU0: echo 1 > nullb0/power CPU1: echo 1 > nullb0/zoned nullb_device_power_store() mutex_lock(&lock) null_add_dev() if (dev->zoned) -> false /* no BLK_FEAT_ZONED */ nullb_device_zoned_store() test_bit(FL_CONFIGURED) -> 0 dev->zoned = true blk_mq_alloc_disk() /* queue is not zoned */ if (nullb->dev->zoned) -> true null_register_zoned_dev() blk_revalidate_disk_zones() blk_revalidate_disk_zones() is then called for a queue that does not have BLK_FEAT_ZONED set, which triggers its WARN_ON_ONCE() and fails the device setup with -EIO: WARNING: CPU: 2 PID: 322 at block/blk-zoned.c:2357 blk_revalidate_disk_zones+0x4c/0x560 Clearing dev->zoned in the same window is worse: the queue is created with BLK_FEAT_ZONED but the zone resources are never initialized, so add_disk() succeeds for a zoned disk that has no zones. And a store that lands after the last dev->zoned test leaves dev->zoned set while dev->zones is still NULL, which null_process_zoned_cmd() dereferences on the first write. Fix this by taking the global lock, which nullb_device_power_store() already holds across null_add_dev() and null_del_dev(), around both the NULLB_DEV_FL_CONFIGURED test and the update of the device configuration. The submit_queues and poll_queues apply callbacks are now called with that lock held, so remove the locking they did themselves. Since the store methods can run as soon as configfs_register_subsystem() returns, that is, before null_init() gets to mutex_init(&lock), also initialize the lock statically with DEFINE_MUTEX(). Fixes: 3bf2bd20734e ("nullb: add configfs interface") Reported-by: syzbot+643a6dd130546afdf1fb@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-block/6a7d0b3f.ac361c09.22ff0a.004c.GAE@google.com/ Signed-off-by: Niklas Cassel <cassel@kernel.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://patch.msgid.link/20260813141456.1625857-2-cassel@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4e1f23f9c33c156be7e313b40695af5a3a834739 ]

The attribute store methods generated with NULLB_DEVICE_ATTR() refuse to
change the configuration of a live device by testing
NULLB_DEV_FL_CONFIGURED, but that flag is only set by
nullb_device_power_store() after null_add_dev() has returned, and the
store methods take no lock at all. configfs only serializes writes to
the same open file (buffer->mutex), so a write to any attribute can run
concurrently with null_add_dev() and change the device configuration
while it is being used.

null_add_dev() reads the configuration several times, e.g. dev->zoned is
read once to set up the queue limits and once to initialize the zone
resources:

  CPU0: echo 1 > nullb0/power         CPU1: echo 1 > nullb0/zoned
  nullb_device_power_store()
    mutex_lock(&lock)
    null_add_dev()
      if (dev->zoned) -> false
        /* no BLK_FEAT_ZONED */       nullb_device_zoned_store()
                                        test_bit(FL_CONFIGURED) -> 0
                                        dev->zoned = true
      blk_mq_alloc_disk()
        /* queue is not zoned */
      if (nullb->dev->zoned) -> true
        null_register_zoned_dev()
          blk_revalidate_disk_zones()

blk_revalidate_disk_zones() is then called for a queue that does not
have BLK_FEAT_ZONED set, which triggers its WARN_ON_ONCE() and fails the
device setup with -EIO:

  WARNING: CPU: 2 PID: 322 at block/blk-zoned.c:2357 blk_revalidate_disk_zones+0x4c/0x560

Clearing dev->zoned in the same window is worse: the queue is created
with BLK_FEAT_ZONED but the zone resources are never initialized, so
add_disk() succeeds for a zoned disk that has no zones. And a store that
lands after the last dev->zoned test leaves dev->zoned set while
dev->zones is still NULL, which null_process_zoned_cmd() dereferences on
the first write.

Fix this by taking the global lock, which nullb_device_power_store()
already holds across null_add_dev() and null_del_dev(), around both the
NULLB_DEV_FL_CONFIGURED test and the update of the device configuration.
The submit_queues and poll_queues apply callbacks are now called with
that lock held, so remove the locking they did themselves.

Since the store methods can run as soon as configfs_register_subsystem()
returns, that is, before null_init() gets to mutex_init(&lock), also
initialize the lock statically with DEFINE_MUTEX().

Fixes: 3bf2bd20734e ("nullb: add configfs interface")
Reported-by: syzbot+643a6dd130546afdf1fb@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-block/6a7d0b3f.ac361c09.22ff0a.004c.GAE@google.com/
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://patch.msgid.link/20260813141456.1625857-2-cassel@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
null_blk: serialize configfs attribute stores with the lock 2026-09-14T11:40:48+00:00 Zizhi Wo wozizhi@huawei.com 2026-07-25T02:25:08+00:00 c70994c2862b05e44728912b2ea9487d31e2aea7 [ Upstream commit 7e7fff51808237703a3a1df6dd5cae1dfd1db86d ] The NULLB_DEVICE_ATTR _store takes no lock: apply_fn attributes (submit_queues, poll_queues) get dev->NAME written again after apply_fn returns, outside its lock; APPLY=NULL attributes are entirely lockless. configfs only serializes stores per-open-file, so concurrent stores on separate fds race. For apply_fn attributes, once one store's apply_fn has reconfigured the hardware, a second (losing) store can still overwrite dev->NAME afterwards. This leaves dev->submit_queues out of sync with the live queue count, which is later caught by the WARN_ON_ONCE() in null_map_queues(). For !apply_fn attributes, power_store()'s null_add_dev() validates and builds the device under "lock" but only sets CONFIGURED afterwards. A store slipping in during this window can change a field mid-setup -- for example, zone_nr_conv can be pushed above nr_zones after it has already been clamped, leading to an out-of-bounds dev->zones[] access. Take "lock" in the macro around the apply_fn call, the CONFIGURED test and the field write, and move it out of nullb_apply_submit_queues()/ nullb_apply_poll_queues() so both paths are covered once. This serializes stores with power_store's setup and with each other. Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after an instance has been configured") Suggested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Link: https://patch.msgid.link/20260725022509.714271-10-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 7e7fff51808237703a3a1df6dd5cae1dfd1db86d ]

The NULLB_DEVICE_ATTR _store takes no lock: apply_fn attributes
(submit_queues, poll_queues) get dev->NAME written again after apply_fn
returns, outside its lock; APPLY=NULL attributes are entirely lockless.
configfs only serializes stores per-open-file, so concurrent stores on
separate fds race.

For apply_fn attributes, once one store's apply_fn has reconfigured the
hardware, a second (losing) store can still overwrite dev->NAME
afterwards. This leaves dev->submit_queues out of sync with the live
queue count, which is later caught by the WARN_ON_ONCE() in
null_map_queues().

For !apply_fn attributes, power_store()'s null_add_dev() validates and
builds the device under "lock" but only sets CONFIGURED afterwards. A store
slipping in during this window can change a field mid-setup -- for example,
zone_nr_conv can be pushed above nr_zones after it has already been
clamped, leading to an out-of-bounds dev->zones[] access.

Take "lock" in the macro around the apply_fn call, the CONFIGURED test and
the field write, and move it out of nullb_apply_submit_queues()/
nullb_apply_poll_queues() so both paths are covered once. This serializes
stores with power_store's setup and with each other.

Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after an instance has been configured")
Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://patch.msgid.link/20260725022509.714271-10-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
null_blk: reject per-device queue resize for shared tag set 2026-09-14T11:40:48+00:00 Zizhi Wo wozizhi@huawei.com 2026-07-25T02:25:06+00:00 baff300541a0012907cdde349728739fe16176d7 [ Upstream commit 1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24 ] When shared_tags is enabled, null_setup_tagset() makes the device use the global tag_set, whose driver_data stays NULL. null_map_queues() therefore falls back to the module-wide g_submit_queues/g_poll_queues instead of any per-device value. Resizing submit_queues or poll_queues via configfs on such a device calls blk_mq_update_nr_hw_queues() on the shared set, shrinking set->nr_hw_queues. __blk_mq_realloc_hw_ctxs() only grows the q->queue_hw_ctx[] allocation, so on shrink it merely exits and NULLs the now-excess hctx slots. null_map_queues(), however, keeps mapping CPUs with the unchanged g_submit_queues/g_poll_queues, so mq_map[] ends up pointing at those NULLed hctx slots. blk_mq_map_swqueue() then dereferences the NULL hctx (hctx->cpumask), crashing the kernel: [ 460.218374] KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f] [ 460.219003] CPU: 24 UID: 0 PID: 1492 Comm: sh Not tainted 7.2.0-rc2+ #67 PREEMPT(full) [ 460.219792] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 [ 460.220452] RIP: 0010:blk_mq_map_swqueue+0x4db/0x1430 ...... [ 460.228977] Call Trace: [ 460.229175] <TASK> [ 460.229354] blk_mq_update_nr_hw_queues+0xd49/0x11c0 [ 460.229779] ? __pfx_blk_mq_update_nr_hw_queues+0x10/0x10 [ 460.230200] nullb_update_nr_hw_queues+0x1a9/0x370 [null_blk] [ 460.230694] nullb_device_submit_queues_store+0xd9/0x170 [null_blk] [ 460.231190] ? __pfx_nullb_device_submit_queues_store+0x10/0x10 [null_blk] [ 460.231776] ? configfs_write_iter+0x35c/0x4e0 [ 460.232122] configfs_write_iter+0x286/0x4e0 [ 460.232460] vfs_write+0x52d/0xd00 [ 460.232779] ? __x64_sys_openat+0x108/0x1d0 [ 460.233106] ? __pfx_vfs_write+0x10/0x10 [ 460.233413] ? fdget_pos+0x1cf/0x4c0 [ 460.233745] ? fput_close+0x133/0x190 [ 460.234038] ? __pfx_expand_files+0x10/0x10 [ 460.234368] ksys_write+0xfc/0x1d0 Reproducer: modprobe null_blk shared_tags=1 submit_queues=64 poll_queues=1 mkdir /sys/kernel/config/nullb/dev echo 1 > /sys/kernel/config/nullb/dev/power echo 1 > /sys/kernel/config/nullb/dev/submit_queues A per-device resize of a shared tag set is meaningless anyway, so reject it with -EINVAL in nullb_update_nr_hw_queues() when the device is bound to the global tag_set. Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after an instance has been configured") Suggested-by: Nilay Shroff <nilay@linux.ibm.com> Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://patch.msgid.link/20260725022509.714271-8-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24 ]

When shared_tags is enabled, null_setup_tagset() makes the device use the
global tag_set, whose driver_data stays NULL. null_map_queues() therefore
falls back to the module-wide g_submit_queues/g_poll_queues instead of any
per-device value.

Resizing submit_queues or poll_queues via configfs on such a device calls
blk_mq_update_nr_hw_queues() on the shared set, shrinking
set->nr_hw_queues.  __blk_mq_realloc_hw_ctxs() only grows the
q->queue_hw_ctx[] allocation, so on shrink it merely exits and NULLs the
now-excess hctx slots. null_map_queues(), however, keeps mapping CPUs with
the unchanged g_submit_queues/g_poll_queues, so mq_map[] ends up pointing
at those NULLed hctx slots. blk_mq_map_swqueue() then dereferences the NULL
hctx (hctx->cpumask), crashing the kernel:

[  460.218374] KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f]
[  460.219003] CPU: 24 UID: 0 PID: 1492 Comm: sh Not tainted 7.2.0-rc2+ #67 PREEMPT(full)
[  460.219792] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014
[  460.220452] RIP: 0010:blk_mq_map_swqueue+0x4db/0x1430
......
[  460.228977] Call Trace:
[  460.229175]  <TASK>
[  460.229354]  blk_mq_update_nr_hw_queues+0xd49/0x11c0
[  460.229779]  ? __pfx_blk_mq_update_nr_hw_queues+0x10/0x10
[  460.230200]  nullb_update_nr_hw_queues+0x1a9/0x370 [null_blk]
[  460.230694]  nullb_device_submit_queues_store+0xd9/0x170 [null_blk]
[  460.231190]  ? __pfx_nullb_device_submit_queues_store+0x10/0x10 [null_blk]
[  460.231776]  ? configfs_write_iter+0x35c/0x4e0
[  460.232122]  configfs_write_iter+0x286/0x4e0
[  460.232460]  vfs_write+0x52d/0xd00
[  460.232779]  ? __x64_sys_openat+0x108/0x1d0
[  460.233106]  ? __pfx_vfs_write+0x10/0x10
[  460.233413]  ? fdget_pos+0x1cf/0x4c0
[  460.233745]  ? fput_close+0x133/0x190
[  460.234038]  ? __pfx_expand_files+0x10/0x10
[  460.234368]  ksys_write+0xfc/0x1d0

Reproducer:
modprobe null_blk shared_tags=1 submit_queues=64 poll_queues=1
mkdir /sys/kernel/config/nullb/dev
echo 1 > /sys/kernel/config/nullb/dev/power
echo 1 > /sys/kernel/config/nullb/dev/submit_queues

A per-device resize of a shared tag set is meaningless anyway, so reject it
with -EINVAL in nullb_update_nr_hw_queues() when the device is bound to the
global tag_set.

Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after an instance has been configured")
Suggested-by: Nilay Shroff <nilay@linux.ibm.com>
Assisted-by: Claude-Code:GLM-5.2
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20260725022509.714271-8-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
null_blk: free zones array on device power-off 2026-09-14T11:40:48+00:00 Zizhi Wo wozizhi@huawei.com 2026-07-25T02:25:04+00:00 0a3afab87124171022fb3579502fa38ef5b311c9 [ Upstream commit 2a6357a9b935a34f5508618fee8a7fffbf7722a8 ] null_init_zoned_dev() allocates dev->zones when a zoned device is powered on, but null_del_dev() never frees it on power-off; dev->zones is only freed later in null_free_dev(), when the configfs directory is removed. If the device is powered off and then on again, null_init_zoned_dev() allocates a new array and overwrites the dev->zones pointer, leaking the previous allocation each power cycle. Free dev->zones in null_del_dev() via null_free_zoned_dev() to solve it. And calling null_free_zoned_dev() in null_free_dev() is no longer necessary because every caller already invokes null_del_dev() first: via nullb_group_drop_item() before nullb_device_release(), in the null_add_dev() error path of null_create_dev(), and in null_destroy_dev(). Remove the redundant call. And take &lock around zone_cond_store() in the two store wrappers to serialize dev->zones check-and-deref against its alloc/free, which already run under &lock. The reason there was no problem before is that only nullb_device_release() or null_exit() frees the dev->zones, which guarantees that subsequent users won't access the configfs interface. Fixes: ca4b2a011948 ("null_blk: add zone support") Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://patch.msgid.link/20260725022509.714271-6-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2a6357a9b935a34f5508618fee8a7fffbf7722a8 ]

null_init_zoned_dev() allocates dev->zones when a zoned device is powered
on, but null_del_dev() never frees it on power-off; dev->zones is only
freed later in null_free_dev(), when the configfs directory is removed. If
the device is powered off and then on again, null_init_zoned_dev()
allocates a new array and overwrites the dev->zones pointer, leaking the
previous allocation each power cycle.

Free dev->zones in null_del_dev() via null_free_zoned_dev() to solve it.
And calling null_free_zoned_dev() in null_free_dev() is no longer necessary
because every caller already invokes null_del_dev() first: via
nullb_group_drop_item() before nullb_device_release(), in the
null_add_dev() error path of null_create_dev(), and in null_destroy_dev().
Remove the redundant call.

And take &lock around zone_cond_store() in the two store wrappers to
serialize dev->zones check-and-deref against its alloc/free, which already
run under &lock. The reason there was no problem before is that only
nullb_device_release() or null_exit() frees the dev->zones, which
guarantees that subsequent users won't access the configfs interface.

Fixes: ca4b2a011948 ("null_blk: add zone support")
Assisted-by: Claude-Code:GLM-5.2
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20260725022509.714271-6-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
null_blk: free global tag_set on init error path 2026-09-14T11:40:48+00:00 Zizhi Wo wozizhi@huawei.com 2026-07-25T02:25:03+00:00 081cf37e8a0e00cd91d6df53172c9d928790a798 [ Upstream commit 5a1c5ff3a49ba93a1fd0b70537e7a0164071760d ] If shared_tags is enabled, null_setup_tagset() allocates the global tag_set via null_init_global_tag_set(). If device creation later fails, err_dev destroys the default devices and calls unregister_blkdev(), but never frees the global tag_set. Since module init failed, null_exit() is never invoked, so the global tag_set's tags and maps are permanently leaked. Free the global tag_set in err_dev, matching null_exit() which does if (tag_set.ops) blk_mq_free_tag_set(&tag_set). Fixes: 82f402fefa50 ("null_blk: add support for shared tags") Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Link: https://patch.msgid.link/20260725022509.714271-5-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 5a1c5ff3a49ba93a1fd0b70537e7a0164071760d ]

If shared_tags is enabled, null_setup_tagset() allocates the global tag_set
via null_init_global_tag_set(). If device creation later fails, err_dev
destroys the default devices and calls unregister_blkdev(), but never frees
the global tag_set. Since module init failed, null_exit() is never invoked,
so the global tag_set's tags and maps are permanently leaked.

Free the global tag_set in err_dev, matching null_exit() which does
if (tag_set.ops) blk_mq_free_tag_set(&tag_set).

Fixes: 82f402fefa50 ("null_blk: add support for shared tags")
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://patch.msgid.link/20260725022509.714271-5-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
null_blk: register configfs subsystem after creating default devices 2026-09-14T11:40:48+00:00 Zizhi Wo wozizhi@huawei.com 2026-07-25T02:25:01+00:00 cab9bf5f68f76cd44e0ec92bd4a60c9b83656a36 [ Upstream commit c9d293d6bb0575fcb1f3408129453187e2a28a4e ] In null_init(), configfs_register_subsystem() currently runs before register_blkdev(), so when null_blk is built as a module, a racing mkdir() + poweron from userspace can reach null_add_dev() while null_major is still 0. __add_disk() then hits WARN_ON(disk->minors) (major=0 with minors!=0) and fails: [root@fedora ~]# [ 2366.521436] WARNING: block/genhd.c:476 at __add_disk+0x8a7/0xde0, [ 2366.523552] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib [ 2366.529081] CPU: 26 UID: 0 PID: 1600 Comm: sh Not tainted 7.2.0-rc1+ #66 PREEMPT(full) ...... [ 2366.547251] Call Trace: [ 2366.547575] <TASK> [ 2366.547831] ? _raw_spin_lock+0x84/0xe0 [ 2366.548260] add_disk_fwnode+0x114/0x560 [ 2366.548739] null_add_dev+0x102d/0x1b80 [null_blk] [ 2366.549310] ? __pfx_null_add_dev+0x10/0x10 [null_blk] [ 2366.549906] ? mutex_lock+0xde/0x1c0 [ 2366.550361] ? __pfx_mutex_lock+0x10/0x10 [ 2366.550827] nullb_device_power_store+0x1e7/0x280 [null_blk] [ 2366.551499] ? __pfx_nullb_device_power_store+0x10/0x10 [null_blk] [ 2366.552177] ? __kmalloc_cache_noprof+0x1f5/0x470 [ 2366.552748] ? configfs_write_iter+0x35c/0x4e0 [ 2366.553242] configfs_write_iter+0x286/0x4e0 [ 2366.553787] vfs_write+0x52d/0xd00 [ 2366.554169] ? __pfx_vfs_write+0x10/0x10 [ 2366.554679] ? __pfx___css_rstat_updated+0x10/0x10 [ 2366.555196] ? fdget_pos+0x1cf/0x4c0 [ 2366.555649] ksys_write+0xfc/0x1d0 ...... Additionally, the err_dev path destroys all devices on nullb_list while configfs is still registered. If a racing mkdir() + poweron puts a user device on the list, null_destroy_dev()->null_free_dev() kfrees the user device's nullb_device but /sys/kernel/config/nullb/<name> is still reachable. Any userspace access to the item will trigger a UAF. For simplicity, move configfs_register_subsystem() to the end to solve the problems above. Fixes: 3bf2bd20734e ("nullb: add configfs interface") Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Link: https://patch.msgid.link/20260725022509.714271-3-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit c9d293d6bb0575fcb1f3408129453187e2a28a4e ]

In null_init(), configfs_register_subsystem() currently runs before
register_blkdev(), so when null_blk is built as a module, a racing mkdir()
+ poweron from userspace can reach null_add_dev() while null_major is still
0. __add_disk() then hits WARN_ON(disk->minors) (major=0 with minors!=0)
and fails:

[root@fedora ~]# [ 2366.521436] WARNING: block/genhd.c:476 at __add_disk+0x8a7/0xde0,
[ 2366.523552] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib
[ 2366.529081] CPU: 26 UID: 0 PID: 1600 Comm: sh Not tainted 7.2.0-rc1+ #66 PREEMPT(full)
......
[ 2366.547251] Call Trace:
[ 2366.547575]  <TASK>
[ 2366.547831]  ? _raw_spin_lock+0x84/0xe0
[ 2366.548260]  add_disk_fwnode+0x114/0x560
[ 2366.548739]  null_add_dev+0x102d/0x1b80 [null_blk]
[ 2366.549310]  ? __pfx_null_add_dev+0x10/0x10 [null_blk]
[ 2366.549906]  ? mutex_lock+0xde/0x1c0
[ 2366.550361]  ? __pfx_mutex_lock+0x10/0x10
[ 2366.550827]  nullb_device_power_store+0x1e7/0x280 [null_blk]
[ 2366.551499]  ? __pfx_nullb_device_power_store+0x10/0x10 [null_blk]
[ 2366.552177]  ? __kmalloc_cache_noprof+0x1f5/0x470
[ 2366.552748]  ? configfs_write_iter+0x35c/0x4e0
[ 2366.553242]  configfs_write_iter+0x286/0x4e0
[ 2366.553787]  vfs_write+0x52d/0xd00
[ 2366.554169]  ? __pfx_vfs_write+0x10/0x10
[ 2366.554679]  ? __pfx___css_rstat_updated+0x10/0x10
[ 2366.555196]  ? fdget_pos+0x1cf/0x4c0
[ 2366.555649]  ksys_write+0xfc/0x1d0
......

Additionally, the err_dev path destroys all devices on nullb_list while
configfs is still registered. If a racing mkdir() + poweron puts a user
device on the list, null_destroy_dev()->null_free_dev() kfrees the user
device's nullb_device but /sys/kernel/config/nullb/<name> is still
reachable. Any userspace access to the item will trigger a UAF.

For simplicity, move configfs_register_subsystem() to the end to solve
the problems above.

Fixes: 3bf2bd20734e ("nullb: add configfs interface")
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://patch.msgid.link/20260725022509.714271-3-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
null_blk: use DEFINE_MUTEX for the file-scope mutex 2026-09-14T11:40:48+00:00 Zizhi Wo wozizhi@huawei.com 2026-07-25T02:25:00+00:00 234117949da3b3f9705a21b66094f9f30bbe681d [ Upstream commit 017dac7670909eaea3eb36e6b3b5a8be9ce0a14d ] In null_init(), mutex_init(&lock) currently happens after configfs_register_subsystem(), which exposes the nullb subsystem to userspace. A racing mkdir() into /sys/kernel/config/nullb/ can reach null_find_dev_by_name() -> mutex_lock(&lock) before the mutex is initialized, trigger warning: [ 123.137788] DEBUG_LOCKS_WARN_ON(lock->magic != lock) [ 123.137796] WARNING: kernel/locking/mutex.c:159 at mutex_lock+0x171/0x1c0, CPU#13: mkdir/1301 [ 123.140090] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 ...... [ 123.154926] Call Trace: [ 123.155172] <TASK> [ 123.155419] ? __pfx_mutex_lock+0x10/0x10 [ 123.156181] ? __pfx__raw_spin_lock+0x10/0x10 [ 123.156571] nullb_group_make_group+0x20/0x100 [null_blk] [ 123.157011] configfs_mkdir+0x47b/0xc70 [ 123.157337] ? __pfx_configfs_mkdir+0x10/0x10 [ 123.157719] ? may_create_dentry+0x242/0x2e0 [ 123.158061] vfs_mkdir+0x2a9/0x6c0 [ 123.158352] filename_mkdirat+0x3dc/0x500 [ 123.158710] ? __pfx_filename_mkdirat+0x10/0x10 [ 123.159070] ? strncpy_from_user+0x3a/0x1d0 [ 123.159413] __x64_sys_mkdir+0x6b/0x90 [ 123.159760] do_syscall_64+0xea/0x600 Replace the runtime mutex_init(&lock) with a static DEFINE_MUTEX(lock) declaration to fix this issue. Fixes: 49c3b9266a71 ("block: null_blk: Improve device creation with configfs") Suggested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Link: https://patch.msgid.link/20260725022509.714271-2-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 017dac7670909eaea3eb36e6b3b5a8be9ce0a14d ]

In null_init(), mutex_init(&lock) currently happens after
configfs_register_subsystem(), which exposes the nullb subsystem to
userspace. A racing mkdir() into /sys/kernel/config/nullb/ can reach
null_find_dev_by_name() -> mutex_lock(&lock) before the mutex is
initialized, trigger warning:

[  123.137788] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
[  123.137796] WARNING: kernel/locking/mutex.c:159 at mutex_lock+0x171/0x1c0, CPU#13: mkdir/1301
[  123.140090] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4
......
[  123.154926] Call Trace:
[  123.155172]  <TASK>
[  123.155419]  ? __pfx_mutex_lock+0x10/0x10
[  123.156181]  ? __pfx__raw_spin_lock+0x10/0x10
[  123.156571]  nullb_group_make_group+0x20/0x100 [null_blk]
[  123.157011]  configfs_mkdir+0x47b/0xc70
[  123.157337]  ? __pfx_configfs_mkdir+0x10/0x10
[  123.157719]  ? may_create_dentry+0x242/0x2e0
[  123.158061]  vfs_mkdir+0x2a9/0x6c0
[  123.158352]  filename_mkdirat+0x3dc/0x500
[  123.158710]  ? __pfx_filename_mkdirat+0x10/0x10
[  123.159070]  ? strncpy_from_user+0x3a/0x1d0
[  123.159413]  __x64_sys_mkdir+0x6b/0x90
[  123.159760]  do_syscall_64+0xea/0x600

Replace the runtime mutex_init(&lock) with a static DEFINE_MUTEX(lock)
declaration to fix this issue.

Fixes: 49c3b9266a71 ("block: null_blk: Improve device creation with configfs")
Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://patch.msgid.link/20260725022509.714271-2-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>