From: Jiayuan Chen <jiayuan.chen@linux.dev> mainline inclusion from mainline-v7.1-rc1 commit a0c584fc18056709c8e047a82a6045d6c209f4ce category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9180 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When querying info for an offloaded BPF map or program, bpf_map_offload_info_fill_ns() and bpf_prog_offload_info_fill_ns() obtain the network namespace with get_net(dev_net(offmap->netdev)). However, the associated netdev's netns may be racing with teardown during netns destruction. If the netns refcount has already reached 0, get_net() performs a refcount_t increment on 0, triggering: refcount_t: addition on 0; use-after-free. Although rtnl_lock and bpf_devs_lock ensure the netdev pointer remains valid, they cannot prevent the netns refcount from reaching zero. Fix this by using maybe_get_net() instead of get_net(). maybe_get_net() uses refcount_inc_not_zero() and returns NULL if the refcount is already zero, which causes ns_get_path_cb() to fail and the caller to return -ENOENT -- the correct behavior when the netns is being destroyed. Fixes: 675fc275a3a2d ("bpf: offload: report device information for offloaded programs") Fixes: 52775b33bb507 ("bpf: offload: report device information about offloaded maps") Reported-by: Yinhao Hu <dddddd@hust.edu.cn> Reported-by: Kaiyan Mei <M202472210@hust.edu.cn> Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn> Closes: https://lore.kernel.org/bpf/f0aa3678-79c9-47ae-9e8c-02a3d1df160a@hust.edu.cn... Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20260409023733.168050-1-jiayuan.chen@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- kernel/bpf/offload.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index bd09290e3648..bfd2ce673369 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -277,9 +277,8 @@ static struct ns_common *bpf_prog_offload_info_fill_ns(void *private_data) if (aux->offload) { args->info->ifindex = aux->offload->netdev->ifindex; - net = dev_net(aux->offload->netdev); - get_net(net); - ns = &net->ns; + net = maybe_get_net(dev_net(aux->offload->netdev)); + ns = net ? &net->ns : NULL; } else { args->info->ifindex = 0; ns = NULL; @@ -504,9 +503,8 @@ static struct ns_common *bpf_map_offload_info_fill_ns(void *private_data) if (args->offmap->netdev) { args->info->ifindex = args->offmap->netdev->ifindex; - net = dev_net(args->offmap->netdev); - get_net(net); - ns = &net->ns; + net = maybe_get_net(dev_net(args->offmap->netdev)); + ns = net ? &net->ns : NULL; } else { args->info->ifindex = 0; ns = NULL; -- 2.34.1