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| author | Jiri Benc <jbenc@redhat.com> | 2019-10-09 10:31:24 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2019-10-14 11:43:48 -0700 |
| commit | 9e8acd9c44a0dd52b2922eeb82398c04e356c058 (patch) | |
| tree | 5638d806575c844a9b27561ba1e93d27586602fa /net | |
| parent | 33902b4a4227877896dd9368ac10f4ca0d100de5 (diff) | |
| download | linux-9e8acd9c44a0dd52b2922eeb82398c04e356c058.tar.gz linux-9e8acd9c44a0dd52b2922eeb82398c04e356c058.tar.bz2 linux-9e8acd9c44a0dd52b2922eeb82398c04e356c058.zip | |
bpf: lwtunnel: Fix reroute supplying invalid dst
The dst in bpf_input() has lwtstate field set. As it is of the
LWTUNNEL_ENCAP_BPF type, lwtstate->data is struct bpf_lwt. When the bpf
program returns BPF_LWT_REROUTE, ip_route_input_noref is directly called on
this skb. This causes invalid memory access, as ip_route_input_slow calls
skb_tunnel_info(skb) that expects the dst->lwstate->data to be
struct ip_tunnel_info. This results to struct bpf_lwt being accessed as
struct ip_tunnel_info.
Drop the dst before calling the IP route input functions (both for IPv4 and
IPv6).
Reported by KASAN.
Fixes: 3bd0b15281af ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Oskolkov <posk@google.com>
Link: https://lore.kernel.org/bpf/111664d58fe4e9dd9c8014bb3d0b2dab93086a9e.1570609794.git.jbenc@redhat.com
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/lwt_bpf.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index f93785e5833c..74cfb8b5ab33 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -88,11 +88,16 @@ static int bpf_lwt_input_reroute(struct sk_buff *skb) int err = -EINVAL; if (skb->protocol == htons(ETH_P_IP)) { + struct net_device *dev = skb_dst(skb)->dev; struct iphdr *iph = ip_hdr(skb); + dev_hold(dev); + skb_dst_drop(skb); err = ip_route_input_noref(skb, iph->daddr, iph->saddr, - iph->tos, skb_dst(skb)->dev); + iph->tos, dev); + dev_put(dev); } else if (skb->protocol == htons(ETH_P_IPV6)) { + skb_dst_drop(skb); err = ipv6_stub->ipv6_route_input(skb); } else { err = -EAFNOSUPPORT; |