{"id":"CVE-2025-40054","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix UAF issue in f2fs_merge_page_bio()\n\nAs JY reported in bugzilla [1],\n\nUnable to handle kernel NULL pointer dereference at virtual address 0000000000000000\npc :…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix UAF issue in f2fs_merge_page_bio()\n\nAs JY reported in bugzilla [1],\n\nUnable to handle kernel NULL pointer dereference at virtual address 0000000000000000\npc :…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","published":"2025-10-28","updated":"2026-08-23","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-40054","references":[{"url":"https://git.kernel.org/stable/c/01118321e0c8a5f3ece57d0d377bfc92d83cd210","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1f7b44b4a2b2939f08b279cbb9e6b5dcb8ffea32","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/410337c2301ae78a081e1b5ebbe8ec374fef4cb6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/68e094232dfe5027c4fd2dcded93d2d6800bae04","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7dd611131d82d7fc4212b555eb1103160bdad302","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e193d8953647c8b575830852aa5ea0995b98d2b1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/edf7e9040fc52c922db947f9c6c36f07377c52ea","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00155,"epssPercentile":0.05014,"ingestedAt":"2026-08-23T13:48:04.839Z","slug":"CVE-2025-40054","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix UAF issue in f2fs_merge_page_bio()\n\nAs JY reported in bugzilla [1],\n\nUnable to handle kernel NULL pointer dereference at virtual address 0000000000000000\npc : [0xffffffe51d249484] f2fs_is_cp_guaranteed+0x70/0x98\nlr : [0xffffffe51d24adbc] f2fs_merge_page_bio+0x520/0x6d4\nCPU: 3 UID: 0 PID: 6790 Comm: kworker/u16:3 Tainted: P    B   W  OE      6.12.30-android16-5-maybe-dirty-4k #1 5f7701c9cbf727d1eebe77c89bbbeb3371e895e5\nTainted: [P]=PROPRIETARY_MODULE, [B]=BAD_PAGE, [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE\nWorkqueue: writeback wb_workfn (flush-254:49)\nCall trace:\n f2fs_is_cp_guaranteed+0x70/0x98\n f2fs_inplace_write_data+0x174/0x2f4\n f2fs_do_write_data_page+0x214/0x81c\n f2fs_write_single_data_page+0x28c/0x764\n f2fs_write_data_pages+0x78c/0xce4\n do_writepages+0xe8/0x2fc\n __writeback_single_inode+0x4c/0x4b4\n writeback_sb_inodes+0x314/0x540\n __writeback_inodes_wb+0xa4/0xf4\n wb_writeback+0x160/0x448\n wb_workfn+0x2f0/0x5dc\n process_scheduled_works+0x1c8/0x458\n worker_thread+0x334/0x3f0\n kthread+0x118/0x1ac\n ret_from_fork+0x10/0x20\n\n[1] https://bugzilla.kernel.org/show_bug.cgi?id=220575\n\nThe panic was caused by UAF issue w/ below race condition:\n\nkworker\n- writepages\n - f2fs_write_cache_pages\n  - f2fs_write_single_data_page\n   - f2fs_do_write_data_page\n    - f2fs_inplace_write_data\n     - f2fs_merge_page_bio\n      - add_inu_page\n      : cache page #1 into bio & cache bio in\n        io->bio_list\n  - f2fs_write_single_data_page\n   - f2fs_do_write_data_page\n    - f2fs_inplace_write_data\n     - f2fs_merge_page_bio\n      - add_inu_page\n      : cache page #2 into bio which is linked\n        in io->bio_list\n\t\t\t\t\t\twrite\n\t\t\t\t\t\t- f2fs_write_begin\n\t\t\t\t\t\t: write page #1\n\t\t\t\t\t\t - f2fs_folio_wait_writeback\n\t\t\t\t\t\t  - f2fs_submit_merged_ipu_write\n\t\t\t\t\t\t   - f2fs_submit_write_bio\n\t\t\t\t\t\t   : submit bio which inclues page #1 and #2\n\n\t\t\t\t\t\tsoftware IRQ\n\t\t\t\t\t\t- f2fs_write_end_io\n\t\t\t\t\t\t - fscrypt_free_bounce_page\n\t\t\t\t\t\t : freed bounced page which belongs to page #2\n      - inc_page_count( , WB_DATA_TYPE(data_folio), false)\n      : data_folio points to fio->encrypted_page\n        the bounced page can be freed before\n        accessing it in f2fs_is_cp_guarantee()\n\nIt can reproduce w/ below testcase:\nRun below script in shell #1:\nfor ((i=1;i>0;i++)) do xfs_io -f /mnt/f2fs/enc/file \\\n-c \"pwrite 0 32k\" -c \"fdatasync\"\n\nRun below script in shell #2:\nfor ((i=1;i>0;i++)) do xfs_io -f /mnt/f2fs/enc/file \\\n-c \"pwrite 0 32k\" -c \"fdatasync\"\n\nSo, in f2fs_merge_page_bio(), let's avoid using fio->encrypted_page after\ncommit page into internal ipu cache.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}