CVE-2024-40995

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 6.9.0-rc4-syzkaller-00173-g3cdb45594619

Description The issue is related to a possible infinite loop in the tcf idr check alloc() function, which can cause tasks to hang when a request to add multiple actions with the same index is sent. This holds rtnl lock and causes tasks to hang. The problem can be resolved by returning -EAGAIN to prevent infinite looping while keeping documented behavior. A reproducer for this issue is available in the syzbot bug.

Recommendations To resolve this issue, update the Linux kernel to a version that includes the fix for the infinite loop in tcf idr check alloc(). As a temporary workaround, consider disabling the act api functionality until a patch is available. Restrict access to the vulnerable net/sched component to minimize the risk of exploitation. Avoid using the same index for multiple actions in the act api until the issue is resolved. At the moment, there is no information about a newer version that contains a fix for this vulnerability.