{"id":"CVE-2025-37999","summary":"fs/erofs/fileio: call erofs_onlinefolio_split() after bio_add_folio()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/erofs/fileio: call erofs_onlinefolio_split() after bio_add_folio()\n\nIf bio_add_folio() fails (because it is full),\nerofs_fileio_scan_folio() needs to submit the I/O request via\nerofs_fileio_rq_submit() and allocate a new I/O request with an empty\n`struct bio`.  Then it retries the bio_add_folio() call.\n\nHowever, at this point, erofs_onlinefolio_split() has already been\ncalled which increments `folio-\u003eprivate`; the retry will call\nerofs_onlinefolio_split() again, but there will never be a matching\nerofs_onlinefolio_end() call.  This leaves the folio locked forever\nand all waiters will be stuck in folio_wait_bit_common().\n\nThis bug has been added by commit ce63cb62d794 (\"erofs: support\nunencoded inodes for fileio\"), but was practically unreachable because\nthere was room for 256 folios in the `struct bio` - until commit\n9f74ae8c9ac9 (\"erofs: shorten bvecs[] for file-backed mounts\") which\nreduced the array capacity to 16 folios.\n\nIt was now trivial to trigger the bug by manually invoking readahead\nfrom userspace, e.g.:\n\n posix_fadvise(fd, 0, st.st_size, POSIX_FADV_WILLNEED);\n\nThis should be fixed by invoking erofs_onlinefolio_split() only after\nbio_add_folio() has succeeded.  This is safe: asynchronous completions\ninvoking erofs_onlinefolio_end() will not unlock the folio because\nerofs_fileio_scan_folio() is still holding a reference to be released\nby erofs_onlinefolio_end() at the end.","modified":"2026-04-02T12:47:43.442343Z","published":"2025-05-29T13:15:56.825Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37999.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/61e0fc3312309867e5a3495329dad0286d2a5703"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bbfe756dc3062c1e934f06e5ba39c239aa953b92"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c26076197df348c84cc23e5962d61902e072a0f5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37999.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-37999"},{"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":"ce63cb62d794c98c7631c2296fa845f2a8d0a4a1"},{"fixed":"61e0fc3312309867e5a3495329dad0286d2a5703"},{"fixed":"c26076197df348c84cc23e5962d61902e072a0f5"},{"fixed":"bbfe756dc3062c1e934f06e5ba39c239aa953b92"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-37999.json"}}],"schema_version":"1.7.5"}