{"api_version":"1","generated_at":"2026-10-01T21:10:10+00:00","cve":"CVE-2026-90186","urls":{"html":"https://cve.report/CVE-2026-90186","api":"https://cve.report/api/cve/CVE-2026-90186.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90186","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90186"},"summary":{"title":"null_blk: reject per-device queue resize for shared tag set","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: reject per-device queue resize for shared tag set\n\nWhen shared_tags is enabled, null_setup_tagset() makes the device use the\nglobal tag_set, whose driver_data stays NULL. null_map_queues() therefore\nfalls back to the module-wide g_submit_queues/g_poll_queues instead of any\nper-device value.\n\nResizing submit_queues or poll_queues via configfs on such a device calls\nblk_mq_update_nr_hw_queues() on the shared set, shrinking\nset->nr_hw_queues.  __blk_mq_realloc_hw_ctxs() only grows the\nq->queue_hw_ctx[] allocation, so on shrink it merely exits and NULLs the\nnow-excess hctx slots. null_map_queues(), however, keeps mapping CPUs with\nthe unchanged g_submit_queues/g_poll_queues, so mq_map[] ends up pointing\nat those NULLed hctx slots. blk_mq_map_swqueue() then dereferences the NULL\nhctx (hctx->cpumask), crashing the kernel:\n\n[  460.218374] KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f]\n[  460.219003] CPU: 24 UID: 0 PID: 1492 Comm: sh Not tainted 7.2.0-rc2+ #67 PREEMPT(full)\n[  460.219792] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014\n[  460.220452] RIP: 0010:blk_mq_map_swqueue+0x4db/0x1430\n......\n[  460.228977] Call Trace:\n[  460.229175]  <TASK>\n[  460.229354]  blk_mq_update_nr_hw_queues+0xd49/0x11c0\n[  460.229779]  ? __pfx_blk_mq_update_nr_hw_queues+0x10/0x10\n[  460.230200]  nullb_update_nr_hw_queues+0x1a9/0x370 [null_blk]\n[  460.230694]  nullb_device_submit_queues_store+0xd9/0x170 [null_blk]\n[  460.231190]  ? __pfx_nullb_device_submit_queues_store+0x10/0x10 [null_blk]\n[  460.231776]  ? configfs_write_iter+0x35c/0x4e0\n[  460.232122]  configfs_write_iter+0x286/0x4e0\n[  460.232460]  vfs_write+0x52d/0xd00\n[  460.232779]  ? __x64_sys_openat+0x108/0x1d0\n[  460.233106]  ? __pfx_vfs_write+0x10/0x10\n[  460.233413]  ? fdget_pos+0x1cf/0x4c0\n[  460.233745]  ? fput_close+0x133/0x190\n[  460.234038]  ? __pfx_expand_files+0x10/0x10\n[  460.234368]  ksys_write+0xfc/0x1d0\n\nReproducer:\nmodprobe null_blk shared_tags=1 submit_queues=64 poll_queues=1\nmkdir /sys/kernel/config/nullb/dev\necho 1 > /sys/kernel/config/nullb/dev/power\necho 1 > /sys/kernel/config/nullb/dev/submit_queues\n\nA per-device resize of a shared tag set is meaningless anyway, so reject it\nwith -EINVAL in nullb_update_nr_hw_queues() when the device is bound to the\nglobal tag_set.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:17:13","updated_at":"2026-09-17 17:17:13"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/f609f7bf9ce8c2fc427705c4a9f623a281239d06","name":"https://git.kernel.org/stable/c/f609f7bf9ce8c2fc427705c4a9f623a281239d06","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/baff300541a0012907cdde349728739fe16176d7","name":"https://git.kernel.org/stable/c/baff300541a0012907cdde349728739fe16176d7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9c7bae099ddc92676ad1b7e29dd6c089e5f6196c","name":"https://git.kernel.org/stable/c/9c7bae099ddc92676ad1b7e29dd6c089e5f6196c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24","name":"https://git.kernel.org/stable/c/1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a","name":"https://git.kernel.org/stable/c/fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3e35ad503386a2e8a0e0460530dcbf421c79f6f2","name":"https://git.kernel.org/stable/c/3e35ad503386a2e8a0e0460530dcbf421c79f6f2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90186","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90186","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 45919fbfe1c487c17ea1d198534339a5e8abeae3 9c7bae099ddc92676ad1b7e29dd6c089e5f6196c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 45919fbfe1c487c17ea1d198534339a5e8abeae3 fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 45919fbfe1c487c17ea1d198534339a5e8abeae3 f609f7bf9ce8c2fc427705c4a9f623a281239d06 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 45919fbfe1c487c17ea1d198534339a5e8abeae3 3e35ad503386a2e8a0e0460530dcbf421c79f6f2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 45919fbfe1c487c17ea1d198534339a5e8abeae3 baff300541a0012907cdde349728739fe16176d7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 45919fbfe1c487c17ea1d198534339a5e8abeae3 1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.5","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.188 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.157 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.110 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/block/null_blk/main.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"9c7bae099ddc92676ad1b7e29dd6c089e5f6196c","status":"affected","version":"45919fbfe1c487c17ea1d198534339a5e8abeae3","versionType":"git"},{"lessThan":"fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a","status":"affected","version":"45919fbfe1c487c17ea1d198534339a5e8abeae3","versionType":"git"},{"lessThan":"f609f7bf9ce8c2fc427705c4a9f623a281239d06","status":"affected","version":"45919fbfe1c487c17ea1d198534339a5e8abeae3","versionType":"git"},{"lessThan":"3e35ad503386a2e8a0e0460530dcbf421c79f6f2","status":"affected","version":"45919fbfe1c487c17ea1d198534339a5e8abeae3","versionType":"git"},{"lessThan":"baff300541a0012907cdde349728739fe16176d7","status":"affected","version":"45919fbfe1c487c17ea1d198534339a5e8abeae3","versionType":"git"},{"lessThan":"1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24","status":"affected","version":"45919fbfe1c487c17ea1d198534339a5e8abeae3","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/block/null_blk/main.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.5"},{"lessThan":"5.5","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.188","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.157","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.110","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.188","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.157","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.110","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"5.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"5.5","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: reject per-device queue resize for shared tag set\n\nWhen shared_tags is enabled, null_setup_tagset() makes the device use the\nglobal tag_set, whose driver_data stays NULL. null_map_queues() therefore\nfalls back to the module-wide g_submit_queues/g_poll_queues instead of any\nper-device value.\n\nResizing submit_queues or poll_queues via configfs on such a device calls\nblk_mq_update_nr_hw_queues() on the shared set, shrinking\nset->nr_hw_queues.  __blk_mq_realloc_hw_ctxs() only grows the\nq->queue_hw_ctx[] allocation, so on shrink it merely exits and NULLs the\nnow-excess hctx slots. null_map_queues(), however, keeps mapping CPUs with\nthe unchanged g_submit_queues/g_poll_queues, so mq_map[] ends up pointing\nat those NULLed hctx slots. blk_mq_map_swqueue() then dereferences the NULL\nhctx (hctx->cpumask), crashing the kernel:\n\n[  460.218374] KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f]\n[  460.219003] CPU: 24 UID: 0 PID: 1492 Comm: sh Not tainted 7.2.0-rc2+ #67 PREEMPT(full)\n[  460.219792] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014\n[  460.220452] RIP: 0010:blk_mq_map_swqueue+0x4db/0x1430\n......\n[  460.228977] Call Trace:\n[  460.229175]  <TASK>\n[  460.229354]  blk_mq_update_nr_hw_queues+0xd49/0x11c0\n[  460.229779]  ? __pfx_blk_mq_update_nr_hw_queues+0x10/0x10\n[  460.230200]  nullb_update_nr_hw_queues+0x1a9/0x370 [null_blk]\n[  460.230694]  nullb_device_submit_queues_store+0xd9/0x170 [null_blk]\n[  460.231190]  ? __pfx_nullb_device_submit_queues_store+0x10/0x10 [null_blk]\n[  460.231776]  ? configfs_write_iter+0x35c/0x4e0\n[  460.232122]  configfs_write_iter+0x286/0x4e0\n[  460.232460]  vfs_write+0x52d/0xd00\n[  460.232779]  ? __x64_sys_openat+0x108/0x1d0\n[  460.233106]  ? __pfx_vfs_write+0x10/0x10\n[  460.233413]  ? fdget_pos+0x1cf/0x4c0\n[  460.233745]  ? fput_close+0x133/0x190\n[  460.234038]  ? __pfx_expand_files+0x10/0x10\n[  460.234368]  ksys_write+0xfc/0x1d0\n\nReproducer:\nmodprobe null_blk shared_tags=1 submit_queues=64 poll_queues=1\nmkdir /sys/kernel/config/nullb/dev\necho 1 > /sys/kernel/config/nullb/dev/power\necho 1 > /sys/kernel/config/nullb/dev/submit_queues\n\nA per-device resize of a shared tag set is meaningless anyway, so reject it\nwith -EINVAL in nullb_update_nr_hw_queues() when the device is bound to the\nglobal tag_set."}],"providerMetadata":{"dateUpdated":"2026-09-17T16:07:09.047Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/9c7bae099ddc92676ad1b7e29dd6c089e5f6196c"},{"url":"https://git.kernel.org/stable/c/fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a"},{"url":"https://git.kernel.org/stable/c/f609f7bf9ce8c2fc427705c4a9f623a281239d06"},{"url":"https://git.kernel.org/stable/c/3e35ad503386a2e8a0e0460530dcbf421c79f6f2"},{"url":"https://git.kernel.org/stable/c/baff300541a0012907cdde349728739fe16176d7"},{"url":"https://git.kernel.org/stable/c/1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24"}],"title":"null_blk: reject per-device queue resize for shared tag set","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90186","datePublished":"2026-09-17T16:07:09.047Z","dateReserved":"2026-09-11T19:38:34.791Z","dateUpdated":"2026-09-17T16:07:09.047Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:17:13","lastModifiedDate":"2026-09-17 17:17:13","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90186","Ordinal":"1","Title":"null_blk: reject per-device queue resize for shared tag set","CVE":"CVE-2026-90186","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90186","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: reject per-device queue resize for shared tag set\n\nWhen shared_tags is enabled, null_setup_tagset() makes the device use the\nglobal tag_set, whose driver_data stays NULL. null_map_queues() therefore\nfalls back to the module-wide g_submit_queues/g_poll_queues instead of any\nper-device value.\n\nResizing submit_queues or poll_queues via configfs on such a device calls\nblk_mq_update_nr_hw_queues() on the shared set, shrinking\nset->nr_hw_queues.  __blk_mq_realloc_hw_ctxs() only grows the\nq->queue_hw_ctx[] allocation, so on shrink it merely exits and NULLs the\nnow-excess hctx slots. null_map_queues(), however, keeps mapping CPUs with\nthe unchanged g_submit_queues/g_poll_queues, so mq_map[] ends up pointing\nat those NULLed hctx slots. blk_mq_map_swqueue() then dereferences the NULL\nhctx (hctx->cpumask), crashing the kernel:\n\n[  460.218374] KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f]\n[  460.219003] CPU: 24 UID: 0 PID: 1492 Comm: sh Not tainted 7.2.0-rc2+ #67 PREEMPT(full)\n[  460.219792] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014\n[  460.220452] RIP: 0010:blk_mq_map_swqueue+0x4db/0x1430\n......\n[  460.228977] Call Trace:\n[  460.229175]  <TASK>\n[  460.229354]  blk_mq_update_nr_hw_queues+0xd49/0x11c0\n[  460.229779]  ? __pfx_blk_mq_update_nr_hw_queues+0x10/0x10\n[  460.230200]  nullb_update_nr_hw_queues+0x1a9/0x370 [null_blk]\n[  460.230694]  nullb_device_submit_queues_store+0xd9/0x170 [null_blk]\n[  460.231190]  ? __pfx_nullb_device_submit_queues_store+0x10/0x10 [null_blk]\n[  460.231776]  ? configfs_write_iter+0x35c/0x4e0\n[  460.232122]  configfs_write_iter+0x286/0x4e0\n[  460.232460]  vfs_write+0x52d/0xd00\n[  460.232779]  ? __x64_sys_openat+0x108/0x1d0\n[  460.233106]  ? __pfx_vfs_write+0x10/0x10\n[  460.233413]  ? fdget_pos+0x1cf/0x4c0\n[  460.233745]  ? fput_close+0x133/0x190\n[  460.234038]  ? __pfx_expand_files+0x10/0x10\n[  460.234368]  ksys_write+0xfc/0x1d0\n\nReproducer:\nmodprobe null_blk shared_tags=1 submit_queues=64 poll_queues=1\nmkdir /sys/kernel/config/nullb/dev\necho 1 > /sys/kernel/config/nullb/dev/power\necho 1 > /sys/kernel/config/nullb/dev/submit_queues\n\nA per-device resize of a shared tag set is meaningless anyway, so reject it\nwith -EINVAL in nullb_update_nr_hw_queues() when the device is bound to the\nglobal tag_set.","Type":"Description","Title":"null_blk: reject per-device queue resize for shared tag set"}]}}}