Commit 8897562f authored by Lorenz Bauer's avatar Lorenz Bauer Committed by Martin KaFai Lau
Browse files

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: 9c02bec9 ("bpf, net: Support SO_REUSEPORT sockets with bpf_sk_assign")
Reported-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: default avatarLorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230815-bpf-next-v2-1-95126eaa4c1b@isovalent.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent dda77040

include/net/inet6_hashtables.h

+1 −1
Original line number Diff line number Diff line
@@ -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) {

include/net/inet_hashtables.h

+1 −1
Original line number Diff line number Diff line
@@ -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) {