Advisory [CVE-2026-63820] fix missing read bio submission on large folio error
This security Red Hat Linux advisory covers CVE-2026-63820.
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Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix missing read bio submission on large folio error f2fs_read_data_large_folio() can keep a read bio across multiple readahead folios.
If a later folio hits an error before any of its blocks are added to the bio, folio_in_bio is false and the current error path returns immediately after ending that folio. This can leave the bio accumulated for earlier folios unsubmitted.
Those folios then never receive read completion, and readers can wait indefinitely on the locked folios. Route errors through the common out path so any pending bio is submitted before returning.
Stop consuming more readahead folios once an error is seen, and only wait on and clear the current folio when it was actually added to the bio. A flaw was found in the Linux kernel's f2fs (Flash-Friendly File System) component.
This vulnerability occurs when the `f2fs_read_data_large_folio()` function fails to submit a read block I/O (bio) request if an error is encountered on a subsequent memory page (folio). This can cause earlier folios to remain locked indefinitely, leading to a denial of service (DoS) where affected readers are unable to proceed.
Red Hat severity: not rated. Weakness: CWE-833.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · medium-confidence parse· fetched 8 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 8 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 8 days ago·verify at source
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