Bug 2521489 (CVE-2026-74605) - CVE-2026-74605 kernel: eventfs: Use children field for rcu head and add memory barriers
Summary: CVE-2026-74605 kernel: eventfs: Use children field for rcu head and add memor...
Keywords:
Status: NEW
Alias: CVE-2026-74605
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-22 15:48 UTC by OSIDB Bzimport
Modified: 2026-08-24 12:20 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-08-22 15:48:03 UTC
In the Linux kernel, the following vulnerability has been resolved:

eventfs: Use children field for rcu head and add memory barriers

When an eventfs inode is freed, it sets ei->is_freed and then uses its
ei->list to add it to the srcu link list as the list field is a union with
the rcu list head. As the ei->list is used to iterate over an SRCU
protected list without taking the eventfs_mutex, there's nothing stopping
the iteration over that list to see the ei->rcu instead of the ei->list
and it will read a corrupt target.

To fix this, change the union of the rcu list head with the children list.
On freeing the eventfs inode, set the is_free and execute a smp_wmb()
before adding the eventfs inode to the SRCU list.

On iteration of the ei->children list, at the start, execute a smp_rmb()
and then read the is_freed of the ei to see if the children list is still
valid. If is_freed is set, then the ei_child read is not valid and the
loop should exit immediately.


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