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CVE-2026-90186— null_blk: reject per-device queue resize for shared tag set

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，已修复以下漏洞： null_blk：拒绝共享 tag set 的按设备队列调整（resize） 当启用 时， 会让该设备使用全局的 ，其 保持为 NULL。因此， 会回退到使用模块级别的 / ，而不会使用任何按设备的值。 通过 configfs 对该类设备调整 或 时，会在共享的 set 上调用 ，从而缩小 。 只负责扩展 的分配，因此在缩小时只会直接返回，并将多余的 hctx 槽位置为 NULL。然而， 仍使用未变化的 / 来映射 CPU，导致 最终指向这些被置为 NULL 的 hctx

AI Predicted 5.5 Difficulty: Easy EPSS 0.21% · P11

Possible ATT&CK Techniques 1 AI

T1690 · Prevent Command History Logging

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux 45919fbfe1c487c17ea1d198534339a5e8abeae3< 9c7bae099ddc92676ad1b7e29dd6c089e5f6196c affected
45919fbfe1c487c17ea1d198534339a5e8abeae3< fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a affected
45919fbfe1c487c17ea1d198534339a5e8abeae3< f609f7bf9ce8c2fc427705c4a9f623a281239d06 affected
45919fbfe1c487c17ea1d198534339a5e8abeae3< 3e35ad503386a2e8a0e0460530dcbf421c79f6f2 affected
45919fbfe1c487c17ea1d198534339a5e8abeae3< baff300541a0012907cdde349728739fe16176d7 affected
45919fbfe1c487c17ea1d198534339a5e8abeae3< 1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24 affected
5.5 affected
< 5.5 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-90186

Vulnerability Information
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Vulnerability Title
null_blk: reject per-device queue resize for shared tag set
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: null_blk: reject per-device queue resize for shared tag set 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 45919fbfe1c487c17ea1d198534339a5e8abeae3 ~ 9c7bae099ddc92676ad1b7e29dd6c089e5f6196c -
Linux Linux 5.5 -

II. Public POCs for CVE-2026-90186

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III. Intelligence Information for CVE-2026-90186

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Patches & Fixes for CVE-2026-90186 (6)

Same Patch Batch · Linux · 2026-09-17 · 600 CVEs total

CVE-2026-90235 9.8 CRITICAL sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
CVE-2026-90104 9.8 CRITICAL NFSv4.1: zero referring call lists before decoding
CVE-2026-90173 9.8 CRITICAL smb: smbdirect: free completion queues with ib_free_cq()
CVE-2026-92489 9.8 CRITICAL xfrm: Fix skb double-free in xfrm_dev_direct_output()
CVE-2026-90151 9.8 CRITICAL NFSv4: remove callback IDR entry on client allocation failure
CVE-2026-90110 9.4 CRITICAL inetpeer: randomize RB-tree node comparison using SipHash
CVE-2026-90230 9.1 CRITICAL nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate()
CVE-2026-90414 9.1 CRITICAL IB/isert: reject PDUs declaring more data than was received
CVE-2026-90413 9.1 CRITICAL IB/isert: reject login PDUs declaring more data than was received
CVE-2026-90380 8.8 HIGH wifi: mt76: mt792x: fix use-after-free in mt76_rx_poll_complete
CVE-2026-93042 8.8 HIGH dmaengine: dw-edma: Terminate all descriptors without callbacks
CVE-2026-90425 8.8 HIGH iommu/tegra241-cmdqv: Require exactly one Stream ID for a vSID
CVE-2026-90240 8.8 HIGH iommu/vt-d: Flush context cache with correct SID when tearing down aliases
CVE-2026-90381 8.8 HIGH wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx()
CVE-2026-90329 8.8 HIGH HID: synchronize input before cleaning up a failed probe
CVE-2026-90357 8.8 HIGH wifi: mt76: mt7915: unlink TWT flow if the MCU rejects the agreement
CVE-2026-90379 8.8 HIGH wifi: mt76: mt7921: Add PCIe AER handler support to prevent system crash
CVE-2026-90162 8.8 HIGH ksmbd: defer publishing granted locks to prevent UAF/double-free race
CVE-2026-93189 8.8 HIGH HID: core: quiesce input in hid_hw_stop() to prevent use-after-free
CVE-2026-90255 8.8 HIGH Bluetooth: hci_conn: fix the SCO setup context lifetime

Showing top 20 of 600 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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