From 8897562f67b3e61ad736cd5c9f307447d33280e4 Mon Sep 17 00:00:00 2001 From: Lorenz Bauer Date: Tue, 15 Aug 2023 09:53:41 +0100 Subject: [PATCH] net: Fix slab-out-of-bounds in inet[6]_steal_sock Kumar reported a KASAN splat in tcp_v6_rcv: bash-5.2# ./test_progs -t btf_skc_cls_ingress ... [ 51.810085] BUG: KASAN: slab-out-of-bounds in tcp_v6_rcv+0x2d7d/0x3440 [ 51.810458] Read of size 2 at addr ffff8881053f038c by task test_progs/226 The problem is that inet[6]_steal_sock accesses sk->sk_protocol without accounting for request or timewait sockets. To fix this we can't just check sock_common->skc_reuseport since that flag is present on timewait sockets. Instead, add a fullsock check to avoid the out of bands access of sk_protocol. Fixes: 9c02bec95954 ("bpf, net: Support SO_REUSEPORT sockets with bpf_sk_assign") Reported-by: Kumar Kartikeya Dwivedi Signed-off-by: Lorenz Bauer Link: https://lore.kernel.org/r/20230815-bpf-next-v2-1-95126eaa4c1b@isovalent.com Signed-off-by: Martin KaFai Lau --- include/net/inet6_hashtables.h | 2 +- include/net/inet_hashtables.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index 284b5ce7205d..533a7337865a 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -116,7 +116,7 @@ struct sock *inet6_steal_sock(struct net *net, struct sk_buff *skb, int doff, if (!sk) return NULL; - if (!prefetched) + if (!prefetched || !sk_fullsock(sk)) return sk; if (sk->sk_protocol == IPPROTO_TCP) { diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 843557223414..3ecfeadbfa06 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -462,7 +462,7 @@ struct sock *inet_steal_sock(struct net *net, struct sk_buff *skb, int doff, if (!sk) return NULL; - if (!prefetched) + if (!prefetched || !sk_fullsock(sk)) return sk; if (sk->sk_protocol == IPPROTO_TCP) {