Bug 2502201 (CVE-2026-63820)

Summary:	CVE-2026-63820 kernel: f2fs: fix missing read bio submission on large folio error
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	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.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-07-19 13:01:34 UTC

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.

Comment 1 Keith Grant 2026-07-20 15:52:23 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071905-CVE-2026-63820-1fc3@gregkh/T