diff options
| author | Willem de Bruijn <willemb@google.com> | 2020-05-25 15:07:40 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-05-26 20:23:46 -0700 |
| commit | 6dd912f82680761d8fb6b1bb274a69d4c7010988 (patch) | |
| tree | d512c61bcf35dfa3057289a23977bacc7e35fd9f | |
| parent | 0a82e230c68860b7286dad8644d9d9f7cfd755d2 (diff) | |
net: check untrusted gso_size at kernel entry
Syzkaller again found a path to a kernel crash through bad gso input:
a packet with gso size exceeding len.
These packets are dropped in tcp_gso_segment and udp[46]_ufo_fragment.
But they may affect gso size calculations earlier in the path.
Now that we have thlen as of commit 9274124f023b ("net: stricter
validation of untrusted gso packets"), check gso_size at entry too.
Fixes: bfd5f4a3d605 ("packet: Add GSO/csum offload support.")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/virtio_net.h | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h index 6f6ade63b04c..88997022a4b5 100644 --- a/include/linux/virtio_net.h +++ b/include/linux/virtio_net.h @@ -31,6 +31,7 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb, { unsigned int gso_type = 0; unsigned int thlen = 0; + unsigned int p_off = 0; unsigned int ip_proto; if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) { @@ -68,7 +69,8 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb, if (!skb_partial_csum_set(skb, start, off)) return -EINVAL; - if (skb_transport_offset(skb) + thlen > skb_headlen(skb)) + p_off = skb_transport_offset(skb) + thlen; + if (p_off > skb_headlen(skb)) return -EINVAL; } else { /* gso packets without NEEDS_CSUM do not set transport_offset. @@ -92,17 +94,25 @@ retry: return -EINVAL; } - if (keys.control.thoff + thlen > skb_headlen(skb) || + p_off = keys.control.thoff + thlen; + if (p_off > skb_headlen(skb) || keys.basic.ip_proto != ip_proto) return -EINVAL; skb_set_transport_header(skb, keys.control.thoff); + } else if (gso_type) { + p_off = thlen; + if (p_off > skb_headlen(skb)) + return -EINVAL; } } if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) { u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size); + if (skb->len - p_off <= gso_size) + return -EINVAL; + skb_shinfo(skb)->gso_size = gso_size; skb_shinfo(skb)->gso_type = gso_type; |