GHSA-2CJV-J4M8-25M8
Vulnerability from github – Published: 2026-10-28 12:31 – Updated: 2026-10-28 12:31In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix data corruption with concurrent writes and O_TRUNC
cifs_do_truncate() flushes dirty pages with filemap_write_and_wait() and truncates the file on the server, but in the old code both operations ran without holding i_rwsem or invalidate_lock. A concurrent buffered write via netfs_perform_write() -- which only needs i_rwsem shared -- could dirty new pages after the flush but before the local truncation, and those pages would be silently discarded by cifs_setsize() -> truncate_pagecache().
Fix by acquiring inode_lock (exclusive i_rwsem) and filemap_invalidate_lock at the top of cifs_do_truncate(), so the entire flush-truncate-resize sequence is atomic with respect to:
- buffered writes (blocked by exclusive i_rwsem, since netfs_start_io_write takes i_rwsem shared),
- read page faults (blocked by exclusive invalidate_lock, since filemap_fault takes it shared),
- writeback collection (blocked by netfs_wb_begin/netfs_wb_end around the server truncate and local resize, since netfs_writepages also acquires the wb lock).
{
"affected": [],
"aliases": [
"CVE-2026-99111"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-28T11:17:30Z",
"severity": null
},
"details": "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 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() -\u003e 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).",
"id": "GHSA-2cjv-j4m8-25m8",
"modified": "2026-10-28T12:31:02Z",
"published": "2026-10-28T12:31:02Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99111"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4d143608a0445443a85c9b29f4c9f8e63d5dbfc9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a8603b52b39f520ea8a34def74c23fba87396d3e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ffa66fdc7d35b890606767c4d2c7ac26b4d90a99"
}
],
"schema_version": "1.4.0",
"severity": []
}
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