{"cve":"CVE-2021-46982","nvd":{"published":"2024-02-28T09:15:37.367","modified":"2026-06-17T04:16:04.217","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: compress: fix race condition of overwrite vs truncate\n\npos_fsstress testcase complains a panic as belew:\n\n------------[ cut here ]------------\nkernel BUG at fs/f2fs/compress.c:1082!\ninvalid opcode: 0000 [#1] SMP PTI\nCPU: 4 PID: 2753477 Comm: kworker/u16:2 Tainted: G           OE     5.12.0-rc1-custom #1\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014\nWorkqueue: writeback wb_workfn (flush-252:16)\nRIP: 0010:prepare_compress_overwrite+0x4c0/0x760 [f2fs]\nCall Trace:\n f2fs_prepare_compress_overwrite+0x5f/0x80 [f2fs]\n f2fs_write_cache_pages+0x468/0x8a0 [f2fs]\n f2fs_write_data_pages+0x2a4/0x2f0 [f2fs]\n do_writepages+0x38/0xc0\n __writeback_single_inode+0x44/0x2a0\n writeback_sb_inodes+0x223/0x4d0\n __writeback_inodes_wb+0x56/0xf0\n wb_writeback+0x1dd/0x290\n wb_workfn+0x309/0x500\n process_one_work+0x220/0x3c0\n worker_thread+0x53/0x420\n kthread+0x12f/0x150\n ret_from_fork+0x22/0x30\n\nThe root cause is truncate() may race with overwrite as below,\nso that one reference count left in page can not guarantee the\npage attaching in mapping tree all the time, after truncation,\nlater find_lock_page() may return NULL pointer.\n\n- prepare_compress_overwrite\n - f2fs_pagecache_get_page\n - unlock_page\n\t\t\t\t\t- f2fs_setattr\n\t\t\t\t\t - truncate_setsize\n\t\t\t\t\t  - truncate_inode_page\n\t\t\t\t\t   - delete_from_page_cache\n - find_lock_page\n\nFix this by avoiding referencing updated page.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","score":4.7},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/5639b73fd3bc6fc8ca72e3a9ac15aacaabd7ebff","https://git.kernel.org/stable/c/64acb100fe3beb5d20184d0ae3307235bd3555c4","https://git.kernel.org/stable/c/936158b15e2648253afb824d252c910c496d34b5","https://git.kernel.org/stable/c/a949dc5f2c5cfe0c910b664650f45371254c0744","https://git.kernel.org/stable/c/5639b73fd3bc6fc8ca72e3a9ac15aacaabd7ebff"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:45:59.823092188+00:00"},"epss":{"cve":"CVE-2021-46982","score":0.00179,"percentile":0.07446,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}