Bug 2502251 (CVE-2026-63802) - CVE-2026-63802 kernel: blk-cgroup: fix UAF in __blkcg_rstat_flush()
Summary: CVE-2026-63802 kernel: blk-cgroup: fix UAF in __blkcg_rstat_flush()
Keywords:
Status: NEW
Alias: CVE-2026-63802
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-19 13:04 UTC by OSIDB Bzimport
Modified: 2026-10-09 08:58 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:67468 0 None None None 2026-09-15 00:47:06 UTC
Red Hat Product Errata RHSA-2026:67469 0 None None None 2026-09-15 00:24:44 UTC
Red Hat Product Errata RHSA-2026:71232 0 None None None 2026-09-24 05:52:40 UTC
Red Hat Product Errata RHSA-2026:71233 0 None None None 2026-09-24 03:01:00 UTC
Red Hat Product Errata RHSA-2026:79783 0 None None None 2026-10-09 08:58:07 UTC

Description OSIDB Bzimport 2026-07-19 13:04:06 UTC 
In the Linux kernel, the following vulnerability has been resolved:

blk-cgroup: fix UAF in __blkcg_rstat_flush()

When multiple blkgs in the same blkcg are released concurrently,
a use-after-free can occur. The race happens when one blkg's
__blkcg_rstat_flush() removes another blkg's iostat entries via
llist_del_all(). The second blkg sees an empty list and proceeds
to free itself while the first is still iterating over its entries.

Move the flush from __blkg_release() (RCU callback) to blkg_release()
(before call_rcu). This ensures the RCU grace period waits for any
concurrent flush's rcu_read_lock() section to complete before freeing.
Comment 1 Keith Grant 2026-07-20 15:06:02 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071901-CVE-2026-63802-1c53@gregkh/T
Comment 5 Jon Orris 2026-09-15 00:24:43 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:67469 https://access.redhat.com/errata/RHSA-2026:67469
Comment 6 Jon Orris 2026-09-15 00:47:04 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:67468 https://access.redhat.com/errata/RHSA-2026:67468
Comment 7 Jon Orris 2026-09-24 03:00:59 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:71233 https://access.redhat.com/errata/RHSA-2026:71233
Comment 8 Jon Orris 2026-09-24 05:52:39 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:71232 https://access.redhat.com/errata/RHSA-2026:71232
Comment 10 Jon Orris 2026-10-09 08:58:06 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

Via RHSA-2026:79783 https://access.redhat.com/errata/RHSA-2026:79783
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