Re: [PATCH ver.2] gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()

On Wed, Feb 14, 2024 at 07:27:33PM +0300, kovalev@altlinux.org wrote:

From: Vasiliy Kovalev kovalev@altlinux.org

The gtp_net_ops pernet operations structure for the subsystem must be registered before registering the generic netlink family.

Thanks for finding a remedy for this.

If your fix is correct, (I didn't test your patch yet) then maybe this needs to be fixed in a few more spots in the tree?

net/devlink/core.c-static int __init devlink_init(void) net/devlink/core.c-{ net/devlink/core.c- int err; net/devlink/core.c- net/devlink/core.c- err = genl_register_family(&devlink_nl_family); net/devlink/core.c- if (err) net/devlink/core.c- goto out; net/devlink/core.c: err = register_pernet_subsys(&devlink_pernet_ops); net/devlink/core.c- if (err)

net/handshake/netlink.c- ret = genl_register_family(&handshake_nl_family); net/handshake/netlink.c- if (ret) { net/handshake/netlink.c- pr_warn("handshake: netlink registration failed (%d)\n", ret); net/handshake/netlink.c- handshake_req_hash_destroy(); net/handshake/netlink.c- return ret; net/handshake/netlink.c- } net/handshake/netlink.c- net/handshake/netlink.c- /* net/handshake/netlink.c- * ORDER: register_pernet_subsys must be done last. net/handshake/netlink.c- * net/handshake/netlink.c- * If initialization does not make it past pernet_subsys net/handshake/netlink.c- * registration, then handshake_net_id will remain 0. That net/handshake/netlink.c- * shunts the handshake consumer API to return ENOTSUPP net/handshake/netlink.c- * to prevent it from dereferencing something that hasn't net/handshake/netlink.c- * been allocated. net/handshake/netlink.c- */ net/handshake/netlink.c: ret = register_pernet_subsys(&handshake_genl_net_ops);

net/ipv4/tcp_metrics.c: ret = register_pernet_subsys(&tcp_net_metrics_ops); net/ipv4/tcp_metrics.c- if (ret < 0) net/ipv4/tcp_metrics.c- panic("Could not register tcp_net_metrics_ops\n"); net/ipv4/tcp_metrics.c- net/ipv4/tcp_metrics.c- ret = genl_register_family(&tcp_metrics_nl_family); net/ipv4/tcp_metrics.c- if (ret < 0) net/ipv4/tcp_metrics.c- panic("Could not register tcp_metrics generic netlink\n"); net/ipv4/tcp_metrics.c-}

net/ipv6/ioam6.c-int __init ioam6_init(void) net/ipv6/ioam6.c-{ net/ipv6/ioam6.c: int err = register_pernet_subsys(&ioam6_net_ops); net/ipv6/ioam6.c- if (err) net/ipv6/ioam6.c- goto out; net/ipv6/ioam6.c- net/ipv6/ioam6.c- err = genl_register_family(&ioam6_genl_family); net/ipv6/ioam6.c- if (err) net/ipv6/ioam6.c- goto out_unregister_pernet_subsys;

net/ipv6/seg6.c- err = genl_register_family(&seg6_genl_family); net/ipv6/seg6.c- if (err) net/ipv6/seg6.c- goto out; net/ipv6/seg6.c- net/ipv6/seg6.c: err = register_pernet_subsys(&ip6_segments_ops); net/ipv6/seg6.c- if (err) net/ipv6/seg6.c- goto out_unregister_genl;

net/netlink/genetlink.c- err = genl_register_family(&genl_ctrl); net/netlink/genetlink.c- if (err < 0) net/netlink/genetlink.c- goto problem; net/netlink/genetlink.c- net/netlink/genetlink.c: err = register_pernet_subsys(&genl_pernet_ops); net/netlink/genetlink.c- if (err) net/netlink/genetlink.c- goto problem;

Syzkaller hit 'general protection fault in gtp_genl_dump_pdp' bug:

[...]

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index b1919278e931f4..2129ae42c70304 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1907,20 +1907,20 @@ static int __init gtp_init(void) if (err < 0) goto error_out;

• err = genl_register_family(&gtp_genl_family);

• err = register_pernet_subsys(&gtp_net_ops); if (err < 0) goto unreg_rtnl_link;

• err = register_pernet_subsys(&gtp_net_ops);

• err = genl_register_family(&gtp_genl_family); if (err < 0)

• goto unreg_genl_family;
  

• goto unreg_pernet_subsys;
  

pr_info("GTP module loaded (pdp ctx size %zd bytes)\n", sizeof(struct pdp_ctx)); return 0; -unreg_genl_family:

• genl_unregister_family(&gtp_genl_family);

+unreg_pernet_subsys:

• unregister_pernet_subsys(&gtp_net_ops);

unreg_rtnl_link: rtnl_link_unregister(&gtp_link_ops); error_out: -- 2.33.8