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CVE PROGRAM SOURCE RECORD9.8 Critical

CVE-2026-68388

smb/client: handle overlapping allocated ranges in fallocate

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: smb/client: handle overlapping allocated ranges in fallocate smb3_simple_fallocate_range() can skip holes when an allocated range returned by the server starts before the current fallocate offset. The skipped hole is not zero-filled, but fallocate still returns success. A later write to that hole may therefore fail with ENOSPC. The function queries allocated ranges so that it can preserve existing contents and write zeroes only into holes. However, the server may return a range that starts before the current fallocate offset. For example, assume the fallocate request is [100, 400) and the only allocated range returned by the server is [0, 200): Request: [100, 400) Server range: [ 0, 200) allocated Correct: [100, 200) allocated data, skip [200, 400) hole, zero-fill Current: [100, 300) skipped [300, 400) zero-filled afterwards The current code adds the full server range length, 200, to the current offset 100 and moves to 300. As a result, the hole in [200, 300) is skipped without being zero-filled. Fix this by advancing only over the part of the allocated range that overlaps the current fallocate offset. Ignore ranges that end before the current offset and reject ranges whose end offset overflows. This also prevents a malformed range length from causing an out-of-bounds zero-buffer read.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • c406bb9ece6ef63721daab106f132ff4b4234e81 to < aeb58a4eb39a7ff4d7782b4f4ada0fda5e0675d2affected
  • 966a3cb7c7db786452a87afdc3b48858fc4d4d6b to < 01719883235507b1585e4c51e320d9a7113dc698affected
  • 966a3cb7c7db786452a87afdc3b48858fc4d4d6b to < f47c7277c03a636fcc3a57969f2dc09567b3c050affected
  • 966a3cb7c7db786452a87afdc3b48858fc4d4d6b to < 437637f5ff3f573b2edf8571de91fb00a21eb4e6affected
  • 966a3cb7c7db786452a87afdc3b48858fc4d4d6b to < 377fe3e583e46369ee1004d5cfe12271d6589a68affected
  • 966a3cb7c7db786452a87afdc3b48858fc4d4d6b to < 7e08ab7a061b17ac1989a225c6afb53f44a86808affected
  • 966a3cb7c7db786452a87afdc3b48858fc4d4d6b to < a4a09e5142835633fffbde68bd0a039ba4d4bf97affected
  • 966a3cb7c7db786452a87afdc3b48858fc4d4d6b to < b09ae45d85dc816987a71db9eebc54b0ae288e94affected
  • 2f9f4a2d0e6fcf0673ed51195e06e47abe966900affected
  • 5e397c943424de94879830e72c95f2679e297a76affected
  • 5.10.50 to < 5.10.265affected
  • 5.12.17 to < 5.13affected
  • 5.13.2 to < 5.14affected

Linux Linux

Default version status: affected

  • 5.14affected
  • 0 to < 5.14unaffected
  • 5.10.265 to ≤ 5.10.*unaffected
  • 5.15.216 to ≤ 5.15.*unaffected
  • 6.1.183 to ≤ 6.1.*unaffected
  • 6.6.148 to ≤ 6.6.*unaffected
  • 6.12.101 to ≤ 6.12.*unaffected
  • 6.18.42 to ≤ 6.18.*unaffected
  • 7.1.6 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References