{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-47256 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2021-47256 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 May 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-2021-47256 and fix it if it is affected.\n\nWhat it is: CVE-2021-47256 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 May 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-2021-47256 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-2021-47256/ (Markdown: https://insights.sbomify.com/CVE-2021-47256/index.md)","id":"CVE-2021-47256","markdown":"https://insights.sbomify.com/CVE-2021-47256/index.md","name":"CVE-2021-47256","record":{"aliases":["DEBIAN-CVE-2021-47256","GHSA-p52g-5qgx-4crw","UBUNTU-CVE-2021-47256"],"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 local attacker can trigger a kernel panic via a race condition in memory failure handling, causing a denial of service.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/memory-failure: make sure wait for page writeback in memory_failure\n\nOur syzkaller trigger the \"BUG_ON(!list_empty(\u0026inode-\u003ei_wb_list))\" in\nclear_inode:\n\n  kernel BUG at fs/inode.c:519!\n  Internal error: Oops - BUG: 0 [#1] SMP\n  Modules linked in:\n  Process syz-executor.0 (pid: 249, stack limit = 0x00000000a12409d7)\n  CPU: 1 PID: 249 Comm: syz-executor.0 Not tainted 4.19.95\n  Hardware name: linux,dummy-virt (DT)\n  pstate: 80000005 (Nzcv daif -PAN -UAO)\n  pc : clear_inode+0x280/0x2a8\n  lr : clear_inode+0x280/0x2a8\n  Call trace:\n    clear_inode+0x280/0x2a8\n    ext4_clear_inode+0x38/0xe8\n    ext4_free_inode+0x130/0xc68\n    ext4_evict_inode+0xb20/0xcb8\n    evict+0x1a8/0x3c0\n    iput+0x344/0x460\n    do_unlinkat+0x260/0x410\n    __arm64_sys_unlinkat+0x6c/0xc0\n    el0_svc_common+0xdc/0x3b0\n    el0_svc_handler+0xf8/0x160\n    el0_svc+0x10/0x218\n  Kernel panic - not syncing: Fatal exception\n\nA crash dump of this problem show that someone called __munlock_pagevec\nto clear page LRU without lock_page: do_mmap -\u003e mmap_region -\u003e do_munmap\n-\u003e munlock_vma_pages_range -\u003e __munlock_pagevec.\n\nAs a result memory_failure will call identify_page_state without\nwait_on_page_writeback.  And after truncate_error_page clear the mapping\nof this page.  end_page_writeback won't call sb_clear_inode_writeback to\nclear inode-\u003ei_wb_list.  That will trigger BUG_ON in clear_inode!\n\nFix it by checking PageWriteback too to help determine should we skip\nwait_on_page_writeback.","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":"mm/memory-failure: make sure wait for page writeback in memory_failure","id":"CVE-2021-47256","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"denial_of_service","year":"2021"},"n_packages":0,"n_references":6,"next":{"headline":"net: ieee802154: fix null deref in parse dev addr","id":"CVE-2021-47257"},"packages":[],"prev":{"headline":"kvm: LAPIC: Restore guard to prevent illegal APIC register access","id":"CVE-2021-47255"},"products":["Linux"],"published":"2024-05-21","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":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A local attacker can trigger a kernel panic via a race condition in memory failure handling, causing a denial of service.","url":"https://insights.sbomify.com/CVE-2021-47256/"}