{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-46984 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2021-46984 is a high-severity vulnerability in Linux kernel, published on 28 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2021-46984 and fix it if it is affected.\n\nWhat it is: CVE-2021-46984 is a high-severity vulnerability in Linux kernel, published on 28 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2021-46984 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2021-46984/ (Markdown: https://insights.sbomify.com/CVE-2021-46984/index.md)","id":"CVE-2021-46984","markdown":"https://insights.sbomify.com/CVE-2021-46984/index.md","name":"CVE-2021-46984","record":{"aliases":["DEBIAN-CVE-2021-46984","GHSA-4qp7-5rvw-5428","UBUNTU-CVE-2021-46984"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A race condition in the Linux kernel's Kyber I/O scheduler can cause out-of-bounds memory access, potentially leading to system crashes or instability.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":7.8,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-129","name":"Improper Validation of Array Index"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nkyber: fix out of bounds access when preempted\n\n__blk_mq_sched_bio_merge() gets the ctx and hctx for the current CPU and\npasses the hctx to -\u003ebio_merge(). kyber_bio_merge() then gets the ctx\nfor the current CPU again and uses that to get the corresponding Kyber\ncontext in the passed hctx. However, the thread may be preempted between\nthe two calls to blk_mq_get_ctx(), and the ctx returned the second time\nmay no longer correspond to the passed hctx. This \"works\" accidentally\nmost of the time, but it can cause us to read garbage if the second ctx\ncame from an hctx with more ctx's than the first one (i.e., if\nctx-\u003eindex_hw[hctx-\u003etype] \u003e hctx-\u003enr_ctx).\n\nThis manifested as this UBSAN array index out of bounds error reported\nby Jakub:\n\nUBSAN: array-index-out-of-bounds in ../kernel/locking/qspinlock.c:130:9\nindex 13106 is out of range for type 'long unsigned int [128]'\nCall Trace:\n dump_stack+0xa4/0xe5\n ubsan_epilogue+0x5/0x40\n __ubsan_handle_out_of_bounds.cold.13+0x2a/0x34\n queued_spin_lock_slowpath+0x476/0x480\n do_raw_spin_lock+0x1c2/0x1d0\n kyber_bio_merge+0x112/0x180\n blk_mq_submit_bio+0x1f5/0x1100\n submit_bio_noacct+0x7b0/0x870\n submit_bio+0xc2/0x3a0\n btrfs_map_bio+0x4f0/0x9d0\n btrfs_submit_data_bio+0x24e/0x310\n submit_one_bio+0x7f/0xb0\n submit_extent_page+0xc4/0x440\n __extent_writepage_io+0x2b8/0x5e0\n __extent_writepage+0x28d/0x6e0\n extent_write_cache_pages+0x4d7/0x7a0\n extent_writepages+0xa2/0x110\n do_writepages+0x8f/0x180\n __writeback_single_inode+0x99/0x7f0\n writeback_sb_inodes+0x34e/0x790\n __writeback_inodes_wb+0x9e/0x120\n wb_writeback+0x4d2/0x660\n wb_workfn+0x64d/0xa10\n process_one_work+0x53a/0xa80\n worker_thread+0x69/0x5b0\n kthread+0x20b/0x240\n ret_from_fork+0x1f/0x30\n\nOnly Kyber uses the hctx, so fix it by passing the request_queue to\n-\u003ebio_merge() instead. BFQ and mq-deadline just use that, and Kyber can\nmap the queues itself to avoid the mismatch.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"kyber: fix out of bounds access when preempted","id":"CVE-2021-46984","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"race_condition","year":"2021"},"n_packages":0,"n_references":5,"next":{"headline":"ACPI: scan: Fix a memory leak in an error handling path","id":"CVE-2021-46985"},"packages":[],"prev":{"headline":"nvmet-rdma: Fix NULL deref when SEND is completed with error","id":"CVE-2021-46983"},"products":["Linux"],"published":"2024-02-28","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-08-05","vendors":["Linux"]},"summary":"A race condition in the Linux kernel's Kyber I/O scheduler can cause out-of-bounds memory access, potentially leading to system crashes or instability.","url":"https://insights.sbomify.com/CVE-2021-46984/"}