smb: client: flush and commit data before querying allocated ranges
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 5.11, 5.13, 5.14, 6.18.56, 7.2.10
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: flush and commit data before querying allocated ranges The mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior ranges in smb3_simple_fallocate_range() issues FSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server reports as an unallocated hole, to force block allocation without changing file contents. This is unsafe against Windows servers. Per the Win32 documentation, FSCTL_QUERY_ALLOCATED_RANGES only reports ranges that may contain nonzero data and is explicitly not coherent with recently written data: "a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network file] would not necessarily return a correct list of allocated regions. To ensure coherency [...] flush the data to the file" fsx (generic/363) reproduces the resulting corruption against Windows Server 2022: a range is written, an uncached read returns the data, yet the next FSCTL_QUERY_ALLOCATED_RANGES on that range reports it as a whole hole, so the emulation overwrites live data with zeroes. A network trace confirmed the WRITE, the READ returning data and the query returning an empty range list within microseconds. Samba does not exhibit this; its query is coherent with the written data. Write back the dirty pages, drain any outstanding I/O and issue an SMB2 FLUSH to force the server to commit the data before querying the allocated ranges, so the query reflects the data actually present. With this, generic/363 passes against both Windows Server 2022 and Samba over 100000 fsx operations.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From 966a3cb7c7db786452a87afdc3b48858fc4d4d6b · fixed in f82242fe3109a3ef72f429540b5bdde08fbfb0e4; From 966a3cb7c7db786452a87afdc3b48858fc4d4d6b · fixed in bf84e44ff0ed802778eafd7ecb623635379cb506; From 966a3cb7c7db786452a87afdc3b48858fc4d4d6b · fixed in aa994489bd835547c191827acc460192e147032d; From 5.10.50 · fixed in 5.11; From 5.12.17 · fixed in 5.13; From 5.13.2 · fixed in 5.14
- Linux Linux
5.14
- KernelLinux
From 5.14.0 · fixed in 6.18.56; From 6.19.0 · fixed in 7.2.10