From: Martin KaFai Lau kafai@fb.com
commit 4ac30c4b3659efac031818c418beb51e630d512d upstream.
__udp6_lib_err() may be called when handling icmpv6 message. For example, the icmpv6 toobig(type=2). __udp6_lib_lookup() is then called which may call reuseport_select_sock(). reuseport_select_sock() will call into a bpf_prog (if there is one).
reuseport_select_sock() is expecting the skb->data pointing to the transport header (udphdr in this case). For example, run_bpf_filter() is pulling the transport header.
However, in the __udp6_lib_err() path, the skb->data is pointing to the ipv6hdr instead of the udphdr.
One option is to pull and push the ipv6hdr in __udp6_lib_err(). Instead of doing this, this patch follows how the original commit 538950a1b752 ("soreuseport: setsockopt SO_ATTACH_REUSEPORT_[CE]BPF") was done in IPv4, which has passed a NULL skb pointer to reuseport_select_sock().
Fixes: 538950a1b752 ("soreuseport: setsockopt SO_ATTACH_REUSEPORT_[CE]BPF") Cc: Craig Gallek kraig@google.com Signed-off-by: Martin KaFai Lau kafai@fb.com Acked-by: Song Liu songliubraving@fb.com Acked-by: Craig Gallek kraig@google.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/udp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -479,7 +479,7 @@ void __udp6_lib_err(struct sk_buff *skb, struct net *net = dev_net(skb->dev);
sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source, - inet6_iif(skb), udptable, skb); + inet6_iif(skb), udptable, NULL); if (!sk) { __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);