CVE-2024-26740

In the Linux kernel, the following vulnerability has been resolved:

net/sched: act_mirred: use the backlog for mirred ingress

The test Davide added in commit ca22da2fbd69 (act_mirred: use the backlog for nested calls to mirred ingress) hangs our testing VMs every 10 or so runs, with the familiar tcp_v4_rcv -> tcp_v4_rcv deadlock reported by lockdep.

The problem as previously described by Davide (see Link) is that if we reverse flow of traffic with the redirect (egress -> ingress) we may reach the same socket which generated the packet. And we may still be holding its socket lock. The common solution to such deadlocks is to put the packet in the Rx backlog, rather than run the Rx path inline. Do that for all egress -> ingress reversals, not just once we started to nest mirred calls.

In the past there was a concern that the backlog indirection will lead to loss of error reporting / less accurate stats. But the current workaround does not seem to address the issue.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/52f671db18823089a02f07efc04efdb2272ddc17
• https://git.kernel.org/stable/c/60ddea1600bc476e0f5e02bce0e29a460ccbf0be
• https://git.kernel.org/stable/c/7c787888d164689da8b1b115f3ef562c1e843af4
• https://git.kernel.org/stable/c/52f671db18823089a02f07efc04efdb2272ddc17
• https://git.kernel.org/stable/c/60ddea1600bc476e0f5e02bce0e29a460ccbf0be
• https://git.kernel.org/stable/c/7c787888d164689da8b1b115f3ef562c1e843af4