From 63f7ee6d8a78e156e0d10d67e8465085b84f0b78 Mon Sep 17 00:00:00 2001 From: Jacob Wen Date: Wed, 30 Jan 2019 14:55:14 +0800 Subject: l2tp: fix reading optional fields of L2TPv3 [ Upstream commit 4522a70db7aa5e77526a4079628578599821b193 ] Use pskb_may_pull() to make sure the optional fields are in skb linear parts, so we can safely read them later. It's easy to reproduce the issue with a net driver that supports paged skb data. Just create a L2TPv3 over IP tunnel and then generates some network traffic. Once reproduced, rx err in /sys/kernel/debug/l2tp/tunnels will increase. Changes in v4: 1. s/l2tp_v3_pull_opt/l2tp_v3_ensure_opt_in_linear/ 2. s/tunnel->version != L2TP_HDR_VER_2/tunnel->version == L2TP_HDR_VER_3/ 3. Add 'Fixes' in commit messages. Changes in v3: 1. To keep consistency, move the code out of l2tp_recv_common. 2. Use "net" instead of "net-next", since this is a bug fix. Changes in v2: 1. Only fix L2TPv3 to make code simple. To fix both L2TPv3 and L2TPv2, we'd better refactor l2tp_recv_common. It's complicated to do so. 2. Reloading pointers after pskb_may_pull Fixes: f7faffa3ff8e ("l2tp: Add L2TPv3 protocol support") Fixes: 0d76751fad77 ("l2tp: Add L2TPv3 IP encapsulation (no UDP) support") Fixes: a32e0eec7042 ("l2tp: introduce L2TPv3 IP encapsulation support for IPv6") Signed-off-by: Jacob Wen Acked-by: Guillaume Nault Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/l2tp/l2tp_ip.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/l2tp/l2tp_ip.c') diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index 9d77a54e8854..03a696d3bcd9 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -157,6 +157,9 @@ static int l2tp_ip_recv(struct sk_buff *skb) print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length); } + if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) + goto discard_sess; + l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook); l2tp_session_dec_refcount(session); -- cgit v1.2.3