Bug 2493763 (CVE-2026-53303)

Summary: CVE-2026-53303 kernel: f2fs: protect extension_list reading with sb_lock in f2fs_sbi_show()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: unspecifiedCC: 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 filesystem. This vulnerability allows for potential out-of-bounds memory access or the display of stale data. It occurs because the `extension_list` and related counts are read without proper synchronization, enabling a concurrent system file system (sysfs) store operation to modify the list while it is being accessed. This inconsistency can lead to system instability or incorrect information being presented.
 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 2026-06-26 21:06:00 UTC 
In the Linux kernel, the following vulnerability has been resolved:

f2fs: protect extension_list reading with sb_lock in f2fs_sbi_show()

In f2fs_sbi_show(), the extension_list, extension_count and
hot_ext_count are read without holding sbi->sb_lock. If a concurrent
sysfs store modifies the extension list via f2fs_update_extension_list(),
the show path may read inconsistent count and array contents, potentially
leading to out-of-bounds access or displaying stale data.

Fix this by holding sb_lock around the entire extension list read
and format operation.
Comment 1 Mauro Matteo Cascella 2026-06-29 08:22:45 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062619-CVE-2026-53303-adc7@gregkh/T