{"id":"CVE-2026-99111","title":"smb: client: fix data corruption with concurrent writes and O_TRUNC","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix data corruption with concurrent writes and O_TRUNC\n\ncifs_do_truncate() flushes dirty pages with filemap_write_and_wait()\nand truncates the file on the …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 110fee6b9bb58a5c50047fc2594d415f741b591e < 4d143608a0445443a85c9b29f4c9f8e63d5dbfc9","Linux >= 110fee6b9bb58a5c50047fc2594d415f741b591e < ffa66fdc7d35b890606767c4d2c7ac26b4d90a99","Linux >= 110fee6b9bb58a5c50047fc2594d415f741b591e < a8603b52b39f520ea8a34def74c23fba87396d3e","Linux 6.18"],"published":"2026-10-28","updated":"2026-10-28","sourceUpdated":"2026-10-28T10:34:29.053Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99111","references":[{"url":"https://git.kernel.org/stable/c/4d143608a0445443a85c9b29f4c9f8e63d5dbfc9"},{"url":"https://git.kernel.org/stable/c/ffa66fdc7d35b890606767c4d2c7ac26b4d90a99"},{"url":"https://git.kernel.org/stable/c/a8603b52b39f520ea8a34def74c23fba87396d3e"}],"tags":["cve.org"],"ingestedAt":"2026-10-28T11:09:40.452Z","epss":0.00167,"epssPercentile":0.0596,"slug":"CVE-2026-99111","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix data corruption with concurrent writes and O_TRUNC\n\ncifs_do_truncate() flushes dirty pages with filemap_write_and_wait()\nand truncates the file on the server, but in the old code both\noperations ran without holding i_rwsem or invalidate_lock.  A\nconcurrent buffered write via netfs_perform_write() -- which only\nneeds i_rwsem shared -- could dirty new pages after the flush but\nbefore the local truncation, and those pages would be silently\ndiscarded by cifs_setsize() -> truncate_pagecache().\n\nFix by acquiring inode_lock (exclusive i_rwsem) and\nfilemap_invalidate_lock at the top of cifs_do_truncate(), so the\nentire flush-truncate-resize sequence is atomic with respect to:\n\n  - buffered writes (blocked by exclusive i_rwsem, since\n    netfs_start_io_write takes i_rwsem shared),\n  - read page faults (blocked by exclusive invalidate_lock, since\n    filemap_fault takes it shared),\n  - writeback collection (blocked by netfs_wb_begin/netfs_wb_end\n    around the server truncate and local resize, since\n    netfs_writepages also acquires the wb lock).\n\n## Affected\n\n- `Linux >= 110fee6b9bb58a5c50047fc2594d415f741b591e < 4d143608a0445443a85c9b29f4c9f8e63d5dbfc9`\n- `Linux >= 110fee6b9bb58a5c50047fc2594d415f741b591e < ffa66fdc7d35b890606767c4d2c7ac26b4d90a99`\n- `Linux >= 110fee6b9bb58a5c50047fc2594d415f741b591e < a8603b52b39f520ea8a34def74c23fba87396d3e`\n- `Linux 6.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}