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 sockets. I added the check to ensure that we only
every try to perform a reuseport lookup on a supported socket.
It turns out that this isn't necessary at all. struct sock_common contains
a skc_reuseport flag which indicates whether a socket is part of a
reuseport group. inet[6]_lookup_reuseport already check this flag,
so we can't execute an erroneous reuseport lookup by definition.
Remove the unnecessary assertions to fix the out of bounds access.
Fixes: 9c02bec95954 ("bpf, net: Support SO_REUSEPORT sockets with bpf_sk_assign")
Reported-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
---
include/net/inet6_hashtables.h | 10 ----------
include/net/inet_hashtables.h | 10 ----------
2 files changed, 20 deletions(-)
diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index 284b5ce7205d..f9907ed36d54 100644
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -119,16 +119,6 @@ struct sock *inet6_steal_sock(struct net *net, struct sk_buff *skb, int doff,
if (!prefetched)
return sk;
- if (sk->sk_protocol == IPPROTO_TCP) {
- if (sk->sk_state != TCP_LISTEN)
- return sk;
- } else if (sk->sk_protocol == IPPROTO_UDP) {
- if (sk->sk_state != TCP_CLOSE)
- return sk;
- } else {
- return sk;
- }
-
reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff,
saddr, sport, daddr, ntohs(dport),
ehashfn);
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 1177effabed3..57a46993383a 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -465,16 +465,6 @@ struct sock *inet_steal_sock(struct net *net, struct sk_buff *skb, int doff,
if (!prefetched)
return sk;
- if (sk->sk_protocol == IPPROTO_TCP) {
- if (sk->sk_state != TCP_LISTEN)
- return sk;
- } else if (sk->sk_protocol == IPPROTO_UDP) {
- if (sk->sk_state != TCP_CLOSE)
- return sk;
- } else {
- return sk;
- }
-
reuse_sk = inet_lookup_reuseport(net, sk, skb, doff,
saddr, sport, daddr, ntohs(dport),
ehashfn);
---
base-commit: eb62e6aef940fcb1879100130068369d4638088f
change-id: 20230808-bpf-next-a442a095562b
Best regards,
--
Lorenz Bauer <lmb@xxxxxxxxxxxxx>
