From 36626c039267d603804139abe6decb31d5ceff50 Mon Sep 17 00:00:00 2001 From: Martin Willi Date: Mon, 28 Jan 2019 09:35:35 +0100 Subject: [PATCH] esp: Skip TX bytes accounting when sending from a request socket On ESP output, sk_wmem_alloc is incremented for the added padding if a socket is associated to the skb. When replying with TCP SYNACKs over IPsec, the associated sk is a casted request socket, only. Increasing sk_wmem_alloc on a request socket results in a write at an arbitrary struct offset. In the best case, this produces the following WARNING: WARNING: CPU: 1 PID: 0 at lib/refcount.c:102 esp_output_head+0x2e4/0x308 [esp4] refcount_t: addition on 0; use-after-free. CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.0.0-rc3 #2 Hardware name: Marvell Armada 380/385 (Device Tree) [...] [] (esp_output_head [esp4]) from [] (esp_output+0xb8/0x180 [esp4]) [] (esp_output [esp4]) from [] (xfrm_output_resume+0x558/0x664) [] (xfrm_output_resume) from [] (xfrm4_output+0x44/0xc4) [] (xfrm4_output) from [] (tcp_v4_send_synack+0xa8/0xe8) [] (tcp_v4_send_synack) from [] (tcp_conn_request+0x7f4/0x948) [] (tcp_conn_request) from [] (tcp_rcv_state_process+0x2a0/0xe64) [] (tcp_rcv_state_process) from [] (tcp_v4_do_rcv+0xf0/0x1f4) [] (tcp_v4_do_rcv) from [] (tcp_v4_rcv+0xdb8/0xe20) [] (tcp_v4_rcv) from [] (ip_protocol_deliver_rcu+0x2c/0x2dc) [] (ip_protocol_deliver_rcu) from [] (ip_local_deliver_finish+0x48/0x54) [] (ip_local_deliver_finish) from [] (ip_local_deliver+0x54/0xec) [] (ip_local_deliver) from [] (ip_rcv+0x48/0xb8) [] (ip_rcv) from [] (__netif_receive_skb_one_core+0x50/0x6c) [...] The issue triggers only when not using TCP syncookies, as for syncookies no socket is associated. Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible") Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible") Signed-off-by: Martin Willi Signed-off-by: Steffen Klassert --- net/ipv4/esp4.c | 2 +- net/ipv6/esp6.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index 5459f41fc26fa7..10e809b296ec86 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -328,7 +328,7 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info * skb->len += tailen; skb->data_len += tailen; skb->truesize += tailen; - if (sk) + if (sk && sk_fullsock(sk)) refcount_add(tailen, &sk->sk_wmem_alloc); goto out; diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c index 5afe9f83374de5..239d4a65ad6ef2 100644 --- a/net/ipv6/esp6.c +++ b/net/ipv6/esp6.c @@ -296,7 +296,7 @@ int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info skb->len += tailen; skb->data_len += tailen; skb->truesize += tailen; - if (sk) + if (sk && sk_fullsock(sk)) refcount_add(tailen, &sk->sk_wmem_alloc); goto out;