Re: [PATCH v3 net] gtp: fix an use-before-init in gtp_newlink()

[Jakub Kicinski]

On Tue, 27 Oct 2020 20:48:46 +0900 Masahiro Fujiwara wrote:
> *_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
> sends GTP packets while creating new GTP device.
> 
> RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
> <SNIP>
> Call Trace:
>  <IRQ>
>  gtp_encap_recv+0xc2/0x2e0 [gtp]
>  ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
>  udp_queue_rcv_one_skb+0x1fe/0x530
>  udp_queue_rcv_skb+0x40/0x1b0
>  udp_unicast_rcv_skb.isra.0+0x78/0x90
>  __udp4_lib_rcv+0x5af/0xc70
>  udp_rcv+0x1a/0x20
>  ip_protocol_deliver_rcu+0xc5/0x1b0
>  ip_local_deliver_finish+0x48/0x50
>  ip_local_deliver+0xe5/0xf0
>  ? ip_protocol_deliver_rcu+0x1b0/0x1b0
> 
> gtp_encap_enable() should be called after gtp_hastable_new() otherwise
> *_pdp_find() will access the uninitialized hash table.
> 
> Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional")
> Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@xxxxxxxxx>

Applied, thank you!