Re: [PATCH net] gtp: fix use-after-free and null-ptr-deref in gtp_newlink()

On Wed, Feb 28, 2024 at 02:47:03PM +0300, Alexander Ofitserov wrote:

The gtp_link_ops operations structure for the subsystem must be registered after registering the gtp_net_ops pernet operations structure.

A fix for this was already applied, see:

commit 136cfaca22567a03bbb3bf53a43d8cb5748b80ec Author: Vasiliy Kovalev kovalev@altlinux.org Date: Wed Feb 14 19:27:33 2024 +0300

gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 2129ae42c7030..0ddec4cc84093 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1903,26 +1903,26 @@ static int __init gtp_init(void) get_random_bytes(&gtp_h_initval, sizeof(gtp_h_initval));

• err = rtnl_link_register(&gtp_link_ops);

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

BTW, I like that this calls register_pernet_subsys() before rtnl_link_register(), where a rtnetlink request could come before pernet is set up.

• err = register_pernet_subsys(&gtp_net_ops);

• err = rtnl_link_register(&gtp_link_ops); if (err < 0)

• goto unreg_rtnl_link;
  

• goto unreg_pernet_subsys;
  

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

• goto unreg_pernet_subsys;
  

• goto unreg_rtnl_link;
  

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

• unregister_pernet_subsys(&gtp_net_ops);

unreg_rtnl_link: rtnl_link_unregister(&gtp_link_ops); +unreg_pernet_subsys:

• unregister_pernet_subsys(&gtp_net_ops);

error_out: pr_err("error loading GTP module loaded\n"); return err; -- 2.42.1