CVE-2026-74605eventfs: Use children field for rcu head and add memory barriers

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/25d27d5fa8645ab61018c3efec5c69f49280ca7d
• https://git.kernel.org/stable/c/1b95382da85cff3bf0f922ff0275f186abdadfce
• https://git.kernel.org/stable/c/2b80707b9e27671e10840d17c6f8f774c4ad9847
• https://git.kernel.org/stable/c/004f7232e49730448f91665e76bdd7dff8e0c638
• https://git.kernel.org/stable/c/f0ece16ffca7384787b692431961ce202907acf5