__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>
4ac30c4b36