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.