{ "affected": [ { "ranges": [ { "events": [ { "introduced": "378f32bab3714f04c4e0c3aee4129f6703805550" }, { "fixed": "fd7e0dab20837b9ea1eeef7c26f78ace8ac8258c" }, { "fixed": "f0af3ae09fb72382da1a5371bf6761b0264668e4" }, { "fixed": "7341e234927ff215f1d5d0bcfe04b74f53af378d" }, { "fixed": "74eee4ff9698a65b2e6e15dac0e50d6526ad5f20" }, { "fixed": "d47cdadd6e49023f7ee248048463807f1214f1ee" }, { "fixed": "4e4e3eec506247c8f8bd8aaa1eb25e67016681a5" }, { "fixed": "9fd3ffc3c51c9deaba99bd7b338fff2d08f52416" }, { "fixed": "15cdefd0c0522f9d5e12d947fa04f4c11649b699" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" } ] }, { "package": { "ecosystem": "Linux", "name": "Kernel" }, "ranges": [ { "events": [ { "introduced": "5.5.0" }, { "fixed": "5.10.270" } ], "type": "ECOSYSTEM" }, { "events": [ { "introduced": "5.11.0" }, { "fixed": "5.15.221" } ], "type": "ECOSYSTEM" }, { "events": [ { "introduced": "5.16.0" }, { "fixed": "6.1.188" } ], "type": "ECOSYSTEM" }, { "events": [ { "introduced": "6.2.0" }, { "fixed": "6.6.157" } ], "type": "ECOSYSTEM" }, { "events": [ { "introduced": "6.7.0" }, { "fixed": "6.12.110" } ], "type": "ECOSYSTEM" }, { "events": [ { "introduced": "6.13.0" }, { "fixed": "6.18.52" } ], "type": "ECOSYSTEM" }, { "events": [ { "introduced": "6.19.0" }, { "fixed": "7.2.6" } ], "type": "ECOSYSTEM" } ] } ], "database_specific": { "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92501.json" }, "details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: drain in-flight DIO before buffered write fallback\n\ngeneric/746 started failing intermittently on ext3 (no-extent inodes).\nThe test triggers 'Page cache invalidation failure on direct I/O'\nwarnings and subsequent fsync returns -EIO. Adding a 50ms delay\nbetween ext4_buffered_write_iter() and filemap_write_and_wait_range()\nin ext4_dio_write_iter() makes the race almost always reproducible.\n\nOn no-extent inodes, DIO writes to holes cannot use unwritten extents,\nso ext4_iomap_alloc() leaves m_flags=0 and ext4_map_blocks() returns 0.\nThe iomap layer then returns -ENOTBLK, causing fallback to buffered I/O.\n\nThe fallback path in ext4_dio_write_iter() calls\next4_buffered_write_iter() which dirties pages, then does flush and\ninvalidate. However, there's an unprotected window between\next4_buffered_write_iter() returning (with inode lock released) and\nthe subsequent flush+invalidate.\n\nConcurrent async DIO completions from other threads can run\nkiocb_invalidate_post_direct_write() during this window. If pages have\nbeen re-dirtied, post-invalidation finds dirty pages and triggers the\nwarning, setting -EIO in the error sequence.\n\nConsider a file with two 4k extents: [hole][written]. Thread A does\nDIO to the written extent, while thread B does DIO spanning both:\n\n kworker A (4k DIO, allocated block) kworker B (8k DIO, fallback)\n ----------------------------------- ----------------------------\n inode_lock_shared() inode_lock_shared()\n iomap_dio_rw(): iomap_dio_rw():\n kiocb_invalidate_pages -\u003e clean iomap_begin -\u003e -ENOTBLK\n submit_bio (async) dio-\u003esize = 0\n inode_unlock_shared() inode_unlock_shared()\n\n [bio pending in block layer] /* fallback: lock released */\n ext4_buffered_write_iter()\n inode_lock(exclusive)\n generic_perform_write()\n -\u003e dirty pages [0, 8k]\n inode_unlock(exclusive)\n\n /* pages dirty, no lock */\n [bio completes] filemap_write_and_wait_range()\n iomap_dio_complete() -\u003e flush dirty pages\n kiocb_invalidate_post_direct_write() invalidate_mapping_pages()\n invalidate_inode_pages2_range()\n -\u003e finds dirty page!\n -\u003e dio_warn_stale_pagecache()\n -\u003e errseq_set(-EIO)\n\nThis issue can be triggered through normal I/O paths, not just\nintentionally overlapping DIO writes from userspace. For example,\ngeneric/746 uses a loop device where multiple kworkers issue concurrent\nI/O to the backing file. Additionally, when block_size \u003c folio_size,\nnon-overlapping DIO writes that share a large folio can also trigger\nthe race.\n\nAdd inode_dio_wait() in ext4_buffered_write_iter() before\next4_write_checks() to drain all in-flight DIO. This ensures that\nall DIO clears existing pages before submitting IO (via\nkiocb_invalidate_pages()), all BIO waits for all DIO to complete\n(via inode_dio_wait()), and ext4_write_checks() observes the inode\nsize after all completed DIO so that ext4_block_zero_eof() does not\nrace with in-flight DIO, thus eliminating the race.", "id": "CVE-2026-92501", "modified": "2026-09-19T03:30:29.178121028Z", "published": "2026-09-17T16:10:14.753Z", "references": [ { "type": "WEB", "url": "https://git.kernel.org/stable/c/15cdefd0c0522f9d5e12d947fa04f4c11649b699" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/4e4e3eec506247c8f8bd8aaa1eb25e67016681a5" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/7341e234927ff215f1d5d0bcfe04b74f53af378d" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/74eee4ff9698a65b2e6e15dac0e50d6526ad5f20" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/9fd3ffc3c51c9deaba99bd7b338fff2d08f52416" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/d47cdadd6e49023f7ee248048463807f1214f1ee" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/f0af3ae09fb72382da1a5371bf6761b0264668e4" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/fd7e0dab20837b9ea1eeef7c26f78ace8ac8258c" }, { "type": "ADVISORY", "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92501.json" }, { "type": "ADVISORY", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-92501" }, { "type": "PACKAGE", "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git" } ], "schema_version": "1.9.0", "summary": "ext4: drain in-flight DIO before buffered write fallback" }