Description
In 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).
Published: 2026-10-28
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Wed, 28 Oct 2026 13:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux linux
Vendors & Products Linux linux

Wed, 28 Oct 2026 13:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-362

Wed, 28 Oct 2026 10:45:00 +0000

Type Values Removed Values Added
Description In 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).
Title smb: client: fix data corruption with concurrent writes and O_TRUNC
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-28T10:34:29.053Z

Reserved: 2026-09-25T10:25:14.392Z

Link: CVE-2026-99111

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-28T11:17:30.520

Modified: 2026-10-28T11:17:30.520

Link: CVE-2026-99111

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-28T13:30:20Z

Weaknesses