{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-92502", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-16T12:21:13.872Z", "datePublished": "2026-09-17T16:10:15.399Z", "dateUpdated": "2026-10-19T09:04:08.456Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:04:08.456Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: clear stale xarray tags on folios skipped during writeback\n\nIn data=journal mode, the writeback thread can hit the\nWARN_ON_ONCE(sb_rdonly(sb)) in ext4_journal_check_start() while the\nsuperblock is being remounted read-only during reboot:\n\nWorkqueue: writeback wb_workfn (flush-253:0)\nRIP: 0010:ext4_journal_check_start+0x8b/0xd0\nCall Trace:\n __ext4_journal_start_sb+0x3c/0x1e0\n mpage_prepare_extent_to_map+0x4af/0x580\n ext4_do_writepages+0x3c0/0x1080\n ext4_writepages+0xc8/0x1a0\n do_writepages+0xc4/0x180\n __writeback_single_inode+0x45/0x2f0\n writeback_sb_inodes+0x26b/0x5d0\n __writeback_inodes_wb+0x54/0x100\n wb_writeback+0x1ac/0x320\n wb_workfn+0x394/0x470\n\nAnd followed by the warning:\nEXT4-fs warning (device vda1): ext4_evict_inode:195: inode #6263:\ncomm (sd-umount): data will be lost\n\nThis issue is not reproduced every time, but frequently.\nThe reproduction step is to create a VM with 8 CPUs, 16G memory and\nsetup data=journal:\nsudo tune2fs -o journal_data /dev/vda1\nRun fio:\nrm -f fiotest\nfio --name=fiotest --rw=randwrite --bs=4k --runtime=6 --ioengine=libaio\n--iodepth=256 --numjobs=8 --filename=fiotest --filesize=30G\n--group_reporting\nReboot the VM, and check the console output from:\nvirsh console testvm\n\nBut there is no dirty inode, folio_clear_dirty_for_io clears PG_dirty\nbut leaves tags PAGECACHE_TAG_DIRTY and PAGECACHE_TAG_TOWRITE set which\nare only cleared by __folio_start_writeback.\nIn data=journal mode, jbd2 checkpoints the journalled data to its final\nlocation and clears its own dirty flag without touching folio PG_dirty\nor xarray dirty flags.\nThe commit f4a2b42e7891 (\"ext4: fix stale xarray tags after writeback\")\nfixes when PG_dirty is still set but there is no dirty page.\nAnother case is PG_dirty is cleared, but PAGECACHE_TAG_DIRTY and\nPAGECACHE_TAG_TOWRITE is still set. In this case, writeback thread\nchecks clean folio and skips it in mpage_prepare_extent_to_map:\nif (!folio_test_dirty(folio) ||\n ...\n folio_unlcok(folio);\n\tcontinue\n\nAnd never reaches ext4_bio_write_folio where the commit f4a2b42e7891\nclears the stale xarray tags. Print debug logs after the filesystem\nis remounted read-only:\nwritepages RDONLY nrpages=2048 dirtytag=1 wbtag=0 towrite=1 sync=0\nAnd all folios are actually clean:\nfolio idx=3 dirty=0 wb=0 checked=0 dirtybuf=0 jbddirty=0 mapped=1\n...\n\nWe need to clear the xarray stale tags for such clean folios by\ncycling them through writeback in the skip path, the same way\nf4a2b42e7891 does in ext4_bio_write_folio." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/inode.c" ], "versions": [ { "version": "dff4ac75eeeefc4397fe7cf8ce559425bf46b1f7", "lessThan": "f82a4929d0ef7ddf254c1c295ec1dfd24094f2de", "status": "affected", "versionType": "git" }, { "version": "dff4ac75eeeefc4397fe7cf8ce559425bf46b1f7", "lessThan": "a450ab88bfd57b227d72c7a3faad54d16c3fc099", "status": "affected", "versionType": "git" }, { "version": "dff4ac75eeeefc4397fe7cf8ce559425bf46b1f7", "lessThan": "aa0042630b1f7cab735b0a168539281198822586", "status": "affected", "versionType": "git" }, { "version": "dff4ac75eeeefc4397fe7cf8ce559425bf46b1f7", "lessThan": "43ae387c3ae6a11227d096669ddf883e27a39a11", "status": "affected", "versionType": "git" }, { "version": "dff4ac75eeeefc4397fe7cf8ce559425bf46b1f7", "lessThan": "ec524aae479b4b2078c47492b90ec21200bce434", "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/inode.c" ], "versions": [ { "version": "6.2", "status": "affected" }, { "version": "0", "lessThan": "6.2", "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": "6.2", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.12.110" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.18.52" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f82a4929d0ef7ddf254c1c295ec1dfd24094f2de" }, { "url": "https://git.kernel.org/stable/c/a450ab88bfd57b227d72c7a3faad54d16c3fc099" }, { "url": "https://git.kernel.org/stable/c/aa0042630b1f7cab735b0a168539281198822586" }, { "url": "https://git.kernel.org/stable/c/43ae387c3ae6a11227d096669ddf883e27a39a11" }, { "url": "https://git.kernel.org/stable/c/ec524aae479b4b2078c47492b90ec21200bce434" } ], "title": "ext4: clear stale xarray tags on folios skipped during writeback", "x_generator": { "engine": "bippy-1.2.0" } } } }