{"id":"CVE-2026-31715","summary":"f2fs: fix UAF caused by decrementing sbi-\u003enr_pages[] in f2fs_write_end_io()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix UAF caused by decrementing sbi-\u003enr_pages[] in f2fs_write_end_io()\n\nThe xfstests case \"generic/107\" and syzbot have both reported a NULL\npointer dereference.\n\nThe concurrent scenario that triggers the panic is as follows:\n\nF2FS_WB_CP_DATA write callback          umount\n                                        - f2fs_write_checkpoint\n                                         - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA)\n- blk_mq_end_request\n - bio_endio\n  - f2fs_write_end_io\n   : dec_page_count(sbi, F2FS_WB_CP_DATA)\n   : wake_up(&sbi-\u003ecp_wait)\n                                        - kill_f2fs_super\n                                         - kill_block_super\n                                          - f2fs_put_super\n                                           : iput(sbi-\u003enode_inode)\n                                           : sbi-\u003enode_inode = NULL\n   : f2fs_in_warm_node_list\n    - is_node_folio // sbi-\u003enode_inode is NULL and panic\n\nThe root cause is that f2fs_put_super() calls iput(sbi-\u003enode_inode) and\nsets sbi-\u003enode_inode to NULL after sbi-\u003enr_pages[F2FS_WB_CP_DATA] is\ndecremented to zero. As a result, f2fs_in_warm_node_list() may\ndereference a NULL node_inode when checking whether a folio belongs to\nthe node inode, leading to a panic.\n\nThis patch fixes the issue by calling f2fs_in_warm_node_list() before\ndecrementing sbi-\u003enr_pages[F2FS_WB_CP_DATA], thus preventing the\nuse-after-free condition.","modified":"2026-06-23T03:54:20.553153976Z","published":"2026-05-01T13:56:10.591Z","related":["CGA-h5h3-hqvh-gfmp","openSUSE-SU-2026:10793-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31715.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0d40b26377f891e6dcb6efaf8ef9374c99be1b1d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1171f329cf1c175321251ac40fd126150d7ad1e8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/188bb65f247a7a7c62f287c9a263aee3cad96fa5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7be222de96c0f9eee6e65eeb017ef855ee185cfa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7dbdab4430e4654db9aacef12b9b3b8b29ca25cb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/963d2e24d9d92a31e6773b0f642214f10013ebf7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ffb94770dbdfb5411be5d9f44a960b010ec890ad"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31715.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31715"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"50fa53eccf9f911a5b435248a2b0bd484fd82e5e"},{"fixed":"7dbdab4430e4654db9aacef12b9b3b8b29ca25cb"},{"fixed":"ffb94770dbdfb5411be5d9f44a960b010ec890ad"},{"fixed":"0d40b26377f891e6dcb6efaf8ef9374c99be1b1d"},{"fixed":"1171f329cf1c175321251ac40fd126150d7ad1e8"},{"fixed":"7be222de96c0f9eee6e65eeb017ef855ee185cfa"},{"fixed":"963d2e24d9d92a31e6773b0f642214f10013ebf7"},{"fixed":"188bb65f247a7a7c62f287c9a263aee3cad96fa5"},{"fixed":"2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31715.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.19.0"},{"fixed":"5.10.259"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.210"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.176"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.140"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.86"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.25"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.2"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31715.json"}}],"schema_version":"1.7.5"}