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CVE-2025-68794: iomap: adjust read range correctly for non-block-aligned positions

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-01-13 · updated 2026-10-19
• Weakness: CWE-190

Description

In the Linux kernel, the following vulnerability has been resolved: iomap: adjust read range correctly for non-block-aligned positions iomap_adjust_read_range() assumes that the position and length passed in are block-aligned. This is not always the case however, as shown in the syzbot generated case for erofs. This causes too many bytes to be skipped for uptodate blocks, which results in returning the incorrect position and length to read in. If all the blocks are uptodate, this underflows length and returns a position beyond the folio. Fix the calculation to also take into account the block offset when calculating how many bytes can be skipped for uptodate blocks.

Affected products

• Linux kernel: 4.19 — fixed in 6.19

How to fix

Upgrade to a fixed version: Linux kernel 6.19. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/12053695c8ef5410e8cc6c9ed4c0db9cd9c82b3e
• https://git.kernel.org/stable/c/142194fb21afe964d2d194cab1fc357cbf87e899
• https://git.kernel.org/stable/c/275b37a1e5c2c8abd313e8075f6aec9a349f291b
• https://git.kernel.org/stable/c/7aa6bc3e8766990824f66ca76c19596ce10daf3e
• https://git.kernel.org/stable/c/82b60ffbb532d919959702768dca04c3c0500ae5
• https://git.kernel.org/stable/c/b8c9f25fd84328c5fcc4f70c6d1e8f1d4787eaac
• https://git.kernel.org/stable/c/ce20f49ac9194cf81a77f01d1c316d7c17ae753c

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