Linux Kernel up to 7.0.12 iomap iomap_finish_folio_read mapping buffer overflow

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 7.0.12. Impacted is the function iomap_finish_folio_read of the component iomap. This manipulation of the argument mapping causes buffer overflow. This vulnerability is handled as CVE-2026-53165. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.0.12. It has been declared as critical. Affected by this vulnerability is the function iomap_finish_folio_read of the component iomap. The manipulation of the argument mapping with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: iomap: avoid potential null folio->mapping deref during error reporting When a buffered read fails, iomap_finish_folio_read() reports the error with fserror_report_io(folio->mapping->host, ...). This is called after ifs->read_bytes_pending has been decremented by the bytes attempted to be read. For a folio split across multiple read completions, the folio is only guaranteed to stay locked while read_bytes_pending > 0. Once iomap_finish_folio_read() decrements read_bytes_pending, another in-flight read can complete and end the read on the folio, which unlocks it. This allows truncate logic to run and detach the folio (set folio->mapping to NULL). The error reporting path then can dereference a NULL folio->mapping. As reported by Sam Sun, this is the race that can occur: CPU0: failed completion CPU1: final completion CPU2: truncate ----------------------- ---------------------- -------------- read_bytes_pending -= len finished = false /* preempted before fserror_report_io() */ read_bytes_pending -= len finished = true folio_end_read() truncate clears folio->mapping fserror_report_io( folio->mapping->host, ...) ^ NULL deref Fix this by reporting the error first before decrementing ifs->read_bytes_pending.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-53165 since 06/09/2026. The exploitation appears to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 06/25/2026).

Upgrading to version 7.0.13 eliminates this vulnerability. Applying the patch 1ad453817a4077230d1ba88eb0868f05f824449a/2eea7f44b9c8b42fd7d3a1a87c06a7cd1b99c327 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.0.7
• 7.0.8
• 7.0.9
• 7.0.10
• 7.0.11
• 7.0.12

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

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