{"id":"CVE-2026-90186","revision":"527dfc4558894221bfad0e6fdfb78d1e","records":[{"revision":"527dfc4558894221bfad0e6fdfb78d1e","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-90186","aliases":[],"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] \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":0,"publishedAt":"2026-09-17T16:07:09.047+00:00","modifiedAt":"2026-10-19T08:59:23.057+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/block/null_blk/main.c\"\n ],\n \"versions\": [\n {\n \"version\": \"45919fbfe1c487c17ea1d198534339a5e8abeae3\",\n \"lessThan\": \"9c7bae099ddc92676ad1b7e29dd6c089e5f6196c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"45919fbfe1c487c17ea1d198534339a5e8abeae3\",\n \"lessThan\": \"fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"45919fbfe1c487c17ea1d198534339a5e8abeae3\",\n \"lessThan\": \"f609f7bf9ce8c2fc427705c4a9f623a281239d06\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"45919fbfe1c487c17ea1d198534339a5e8abeae3\",\n \"lessThan\": \"3e35ad503386a2e8a0e0460530dcbf421c79f6f2\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"45919fbfe1c487c17ea1d198534339a5e8abeae3\",\n \"lessThan\": \"baff300541a0012907cdde349728739fe16176d7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"45919fbfe1c487c17ea1d198534339a5e8abeae3\",\n \"lessThan\": \"1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/block/null_blk/main.c\"\n ],\n \"versions\": [\n {\n \"version\": \"5.5\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"5.5\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.188\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.157\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.110\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.52\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.6\",\n \"lessThanOrEqual\": \"7.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/9c7bae099ddc92676ad1b7e29dd6c089e5f6196c","https://git.kernel.org/stable/c/fcd53f3e8b758c79c3f2420d28a2a1dce6fda61a","https://git.kernel.org/stable/c/f609f7bf9ce8c2fc427705c4a9f623a281239d06","https://git.kernel.org/stable/c/3e35ad503386a2e8a0e0460530dcbf421c79f6f2","https://git.kernel.org/stable/c/baff300541a0012907cdde349728739fe16176d7","https://git.kernel.org/stable/c/1cdfe2fa62b48728a9b436fbbd3dbe4c11593e24"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-90186","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-90186","identifiers":["CVE-2026-90186"]},"retained":false,"historicalAffected":[]}],"coverage":[]}