Re: [PATCH 6.6 v3 0/3] Set the bpf_net_context before invoking BPF XDP in the TUN driver

On 2025-02-26 10:39:04 [+0100], Ricardo Cañuelo Navarro wrote:

A private syzbot instance reported "KASAN: slab-use-after-free Read in dev_map_enqueue" under some runtime environments.

Upstream patch fecef4cd42c6 ("tun: Assign missing bpf_net_context") fixes the issue. In order to bring this patch to stable v6.6 it's also necessary to bring upstream patch 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") as a dependency.

Just to be clear: A problem exists in v6.6 independent of my doing and 401cb7dae813 happens to fix it? The commit fecef4cd42c6 is a fixup for 401cb7dae813.

If so, can you share syzbot's reproducer and/or backtrace/ report?

Sebastian