kernel/linux.git/drivers/block/null_blk, branch v6.1.186

null_blk: fix UBSAN shift-out-of-bounds when zone_size is 0 or overflows

2026-08-27T12:29:01+00:00

commit 95491fb05105b61050cb623a5e0227eb26aa3525 upstream. null_zone_no() does sect >> ilog2(dev->zone_size_sects). When zone_size_sects is 0, ilog2(0) returns -1, producing shift exponent -1 which UBSAN reports as shift-out-of-bounds. UBSAN: shift-out-of-bounds in drivers/block/null_blk/zoned.c:21:14 shift exponent -1 is negative Call Trace: null_zone_no drivers/block/null_blk/zoned.c:21 [inline] null_process_zoned_cmd+0xf76/0xf80 drivers/block/null_blk/zoned.c:728 null_handle_cmd drivers/block/null_blk/main.c:1455 [inline] null_queue_rq+0x8bc/0xe70 drivers/block/null_blk/main.c:1703 __blk_mq_issue_directly block/blk-mq.c:2694 [inline] blk_mq_try_issue_directly+0x3f4/0x880 block/blk-mq.c:2754 blk_mq_submit_bio+0x20c0/0x2a40 block/blk-mq.c:3208 submit_bio_noacct_nocheck+0x2f4/0xa40 block/blk-core.c:790 block_read_full_folio+0x7a6/0x810 fs/buffer.c:2463 filemap_read_folio+0x12c/0x3a0 mm/filemap.c:2510 read_part_sector+0xb6/0x2b0 block/partitions/core.c:724 adfspart_check_ICS+0xb1/0x960 block/partitions/acorn.c:357 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x851/0x17a0 block/partitions/core.c:695 blkdev_get_whole+0x372/0x510 block/bdev.c:751 add_disk_final block/genhd.c:412 [inline] add_disk_fwnode+0x24b/0x3a0 block/genhd.c:606 null_add_dev+0x130b/0x1d70 drivers/block/null_blk/main.c:2052 nullb_device_power_store+0x240/0x380 drivers/block/null_blk/main.c:501 configfs_write_iter+0x337/0x430 fs/configfs/file.c:229 Syzkaller triggers this by creating a zoned null_blk device via configfs. The Call Trace shows configfs_write_iter in configfs/file.c handling a write to power file, which calls nullb_device_power_store in main.c, which calls null_add_dev in main.c, which calls add_disk in genhd.c, which triggers partition scan via bdev_disk_changed in partitions/core.c. A zoned null_blk device with zone_size 0 should not be legal. Existing code tries to reject it via is_power_of_2() check in zoned.c and !zone_size check in main.c, but syzkaller can still reach null_zone_no() with zone_size_sects 0 via two paths: 1. Direct 0 via configfs: zone_size attribute store in main.c has NULLB_DEVICE_ATTR(zone_size, ulong, NULL) with no validation callback, so echo 0 > zone_size succeeds before power store. If zoned is false at power store time, the !zone_size check in main.c is skipped, and later zoned set true leaves zone_size 0. 2. Large value overflow: mb_to_sects() in zoned.c does (sector_t)mb * SZ_1M >> SECTOR_SHIFT which is mb * 2048. If mb is 1UL << 53 (9PB), mb * 2048 overflows 64-bit to 0. The value is power-of-two so is_power_of_2() passes, but mb_to_sects() returns 0. Check for zero zone_size explicitly in null_init_zoned_dev() in zoned.c, returning -EINVAL with "must be non-zero power-of-two". Check for zero zone_size_sects after mb_to_sects() conversion, returning -EINVAL for overflow case. Keep defensive check in null_zone_no() returning 0 for zero sectors to avoid shift out-of-bounds even if zero slips through. This change should be safe because zone_size is set once in null_init_zoned_dev() under device lock and never changes after, and 0 is never valid for a zoned device. Returning -EINVAL at init time fails device creation early with clear error, while defensive return 0 in null_zone_no() makes zoned command fail via offline zone check. No new locking is introduced. Reported-by: syzbot+abd6a8dca0f2b7726060@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=abd6a8dca0f2b7726060 Link: https://lore.kernel.org/all/6a75205c.01d0871a.3a0d52.0033.GAE@google.com/ Fixes: 8a3cf049af68 ("null_blk: add zoned block device emulation") Cc: stable@vger.kernel.org Assisted-by: Hermes:muse-spark-1.2 syzkaller Signed-off-by: Rik van Riel Reviewed-by: Damien Le Moal Link: https://patch.msgid.link/20260808114239.69167f68@fangorn Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

null_blk: Fix the description of the cache_size module argument

2025-10-15T09:56:27+00:00

[ Upstream commit 7942b226e6b84df13b46b76c01d3b6e07a1b349e ] When executing modinfo null_blk, there is an error in the description of module parameter mbps, and the output information of cache_size is incomplete.The output of modinfo before and after applying this patch is as follows: Before: [...] parm: cache_size:ulong [...] parm: mbps:Cache size in MiB for memory-backed device. Default: 0 (none) (uint) [...] After: [...] parm: cache_size:Cache size in MiB for memory-backed device. Default: 0 (none) (ulong) [...] parm: mbps:Limit maximum bandwidth (in MiB/s). Default: 0 (no limit) (uint) [...] Fixes: 058efe000b31 ("null_blk: add module parameters for 4 options") Signed-off-by: Genjian Zhang Reviewed-by: Damien Le Moal Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

null_blk: Fix return value of nullb_device_power_store()

2024-11-22T14:37:35+00:00

commit d9ff882b54f99f96787fa3df7cd938966843c418 upstream. When powering on a null_blk device that is not already on, the return value ret that is initialized to be count is reused to check the return value of null_add_dev(), leading to nullb_device_power_store() to return null_add_dev() return value (0 on success) instead of "count". So make sure to set ret to be equal to count when there are no errors. Fixes: a2db328b0839 ("null_blk: fix null-ptr-dereference while configuring 'power' and 'submit_queues'") Signed-off-by: Damien Le Moal Reviewed-by: Yu Kuai Reviewed-by: Kanchan Joshi Link: https://lore.kernel.org/r/20240527043445.235267-1-dlemoal@kernel.org Signed-off-by: Jens Axboe Signed-off-by: Xiangyu Chen Signed-off-by: Greg Kroah-Hartman

null_blk: fix null-ptr-dereference while configuring 'power' and 'submit_queues'

2024-11-22T14:37:34+00:00

commit a2db328b0839312c169eb42746ec46fc1ab53ed2 upstream. Writing 'power' and 'submit_queues' concurrently will trigger kernel panic: Test script: modprobe null_blk nr_devices=0 mkdir -p /sys/kernel/config/nullb/nullb0 while true; do echo 1 > submit_queues; echo 4 > submit_queues; done & while true; do echo 1 > power; echo 0 > power; done Test result: BUG: kernel NULL pointer dereference, address: 0000000000000148 Oops: 0000 [#1] PREEMPT SMP RIP: 0010:__lock_acquire+0x41d/0x28f0 Call Trace: lock_acquire+0x121/0x450 down_write+0x5f/0x1d0 simple_recursive_removal+0x12f/0x5c0 blk_mq_debugfs_unregister_hctxs+0x7c/0x100 blk_mq_update_nr_hw_queues+0x4a3/0x720 nullb_update_nr_hw_queues+0x71/0xf0 [null_blk] nullb_device_submit_queues_store+0x79/0xf0 [null_blk] configfs_write_iter+0x119/0x1e0 vfs_write+0x326/0x730 ksys_write+0x74/0x150 This is because del_gendisk() can concurrent with blk_mq_update_nr_hw_queues(): nullb_device_power_store nullb_apply_submit_queues null_del_dev del_gendisk nullb_update_nr_hw_queues if (!dev->nullb) // still set while gendisk is deleted return 0 blk_mq_update_nr_hw_queues dev->nullb = NULL Fix this problem by resuing the global mutex to protect nullb_device_power_store() and nullb_update_nr_hw_queues() from configfs. Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after an instance has been configured") Reported-and-tested-by: Yi Zhang Closes: https://lore.kernel.org/all/CAHj4cs9LgsHLnjg8z06LQ3Pr5cax-+Ps+xT7AP7TPnEjStuwZA@mail.gmail.com/ Signed-off-by: Yu Kuai Reviewed-by: Zhu Yanjun Link: https://lore.kernel.org/r/20240523153934.1937851-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin Signed-off-by: Xiangyu Chen Signed-off-by: Greg Kroah-Hartman

null_blk: Remove usage of the deprecated ida_simple_xx() API

2024-11-22T14:37:34+00:00

commit 95931a245b44ee04f3359ec432e73614d44d8b38 upstream. ida_alloc() and ida_free() should be preferred to the deprecated ida_simple_get() and ida_simple_remove(). This is less verbose. Signed-off-by: Christophe JAILLET Link: https://lore.kernel.org/r/bf257b1078475a415cdc3344c6a750842946e367.1705222845.git.christophe.jaillet@wanadoo.fr Signed-off-by: Jens Axboe Signed-off-by: Xiangyu Chen Signed-off-by: Greg Kroah-Hartman

null_blk: fix validation of block size

2024-07-25T07:49:11+00:00

[ Upstream commit c462ecd659b5fce731f1d592285832fd6ad54053 ] Block size should be between 512 and PAGE_SIZE and be a power of 2. The current check does not validate this, so update the check. Without this patch, null_blk would Oops due to a null pointer deref when loaded with bs=1536 [1]. Link: https://lore.kernel.org/all/87wmn8mocd.fsf@metaspace.dk/ Signed-off-by: Andreas Hindborg Reviewed-by: Ming Lei Link: https://lore.kernel.org/r/20240603192645.977968-1-nmi@metaspace.dk [axboe: remove unnecessary braces and != 0 check] Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

null_blk: Do not allow runt zone with zone capacity smaller then zone size

2024-07-11T10:47:18+00:00

[ Upstream commit b164316808ec5de391c3e7b0148ec937d32d280d ] A zoned device with a smaller last zone together with a zone capacity smaller than the zone size does make any sense as that does not correspond to any possible setup for a real device: 1) For ZNS and zoned UFS devices, all zones are always the same size. 2) For SMR HDDs, all zones always have the same capacity. In other words, if we have a smaller last runt zone, then this zone capacity should always be equal to the zone size. Add a check in null_init_zoned_dev() to prevent a configuration to have both a smaller zone size and a zone capacity smaller than the zone size. Signed-off-by: Damien Le Moal Reviewed-by: Niklas Cassel Reviewed-by: Bart Van Assche Link: https://lore.kernel.org/r/20240530054035.491497-2-dlemoal@kernel.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

null_blk: Print correct max open zones limit in null_init_zoned_dev()

2024-06-21T12:35:55+00:00

commit 233e27b4d21c3e44eb863f03e566d3a22e81a7ae upstream. When changing the maximum number of open zones, print that number instead of the total number of zones. Fixes: dc4d137ee3b7 ("null_blk: add support for max open/active zone limit for zoned devices") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal Reviewed-by: Niklas Cassel Link: https://lore.kernel.org/r/20240528062852.437599-1-dlemoal@kernel.org Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

null_blk: Fix the WARNING: modpost: missing MODULE_DESCRIPTION()

2024-06-12T09:03:49+00:00

[ Upstream commit 9e6727f824edcdb8fdd3e6e8a0862eb49546e1cd ] No functional changes intended. Fixes: f2298c0403b0 ("null_blk: multi queue aware block test driver") Signed-off-by: Zhu Yanjun Reviewed-by: Chaitanya Kulkarni Link: https://lore.kernel.org/r/20240506075538.6064-1-yanjun.zhu@linux.dev Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

null_blk: Fix missing mutex_destroy() at module removal

2024-06-12T09:03:06+00:00

[ Upstream commit 07d1b99825f40f9c0d93e6b99d79a08d0717bac1 ] When a mutex lock is not used any more, the function mutex_destroy should be called to mark the mutex lock uninitialized. Fixes: f2298c0403b0 ("null_blk: multi queue aware block test driver") Signed-off-by: Zhu Yanjun Link: https://lore.kernel.org/r/20240425171635.4227-1-yanjun.zhu@linux.dev Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin