{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-92501", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-16T12:21:13.871Z", "datePublished": "2026-09-17T16:10:14.753Z", "dateUpdated": "2026-10-19T09:04:07.250Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:04:07.250Z" }, "descriptions": [ { "lang": "en", "value": "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 -> clean iomap_begin -> -ENOTBLK\n submit_bio (async) dio->size = 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 -> 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() -> flush dirty pages\n kiocb_invalidate_post_direct_write() invalidate_mapping_pages()\n invalidate_inode_pages2_range()\n -> finds dirty page!\n -> dio_warn_stale_pagecache()\n -> 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 < 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." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/file.c" ], "versions": [ { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "fd7e0dab20837b9ea1eeef7c26f78ace8ac8258c", "status": "affected", "versionType": "git" }, { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "f0af3ae09fb72382da1a5371bf6761b0264668e4", "status": "affected", "versionType": "git" }, { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "7341e234927ff215f1d5d0bcfe04b74f53af378d", "status": "affected", "versionType": "git" }, { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "74eee4ff9698a65b2e6e15dac0e50d6526ad5f20", "status": "affected", "versionType": "git" }, { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "d47cdadd6e49023f7ee248048463807f1214f1ee", "status": "affected", "versionType": "git" }, { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "4e4e3eec506247c8f8bd8aaa1eb25e67016681a5", "status": "affected", "versionType": "git" }, { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "9fd3ffc3c51c9deaba99bd7b338fff2d08f52416", "status": "affected", "versionType": "git" }, { "version": "378f32bab3714f04c4e0c3aee4129f6703805550", "lessThan": "15cdefd0c0522f9d5e12d947fa04f4c11649b699", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/file.c" ], "versions": [ { "version": "5.5", "status": "affected" }, { "version": "0", "lessThan": "5.5", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.110", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "5.10.270" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "5.15.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "6.12.110" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "6.18.52" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/fd7e0dab20837b9ea1eeef7c26f78ace8ac8258c" }, { "url": "https://git.kernel.org/stable/c/f0af3ae09fb72382da1a5371bf6761b0264668e4" }, { "url": "https://git.kernel.org/stable/c/7341e234927ff215f1d5d0bcfe04b74f53af378d" }, { "url": "https://git.kernel.org/stable/c/74eee4ff9698a65b2e6e15dac0e50d6526ad5f20" }, { "url": "https://git.kernel.org/stable/c/d47cdadd6e49023f7ee248048463807f1214f1ee" }, { "url": "https://git.kernel.org/stable/c/4e4e3eec506247c8f8bd8aaa1eb25e67016681a5" }, { "url": "https://git.kernel.org/stable/c/9fd3ffc3c51c9deaba99bd7b338fff2d08f52416" }, { "url": "https://git.kernel.org/stable/c/15cdefd0c0522f9d5e12d947fa04f4c11649b699" } ], "title": "ext4: drain in-flight DIO before buffered write fallback", "x_generator": { "engine": "bippy-1.2.0" } } } }