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| author | Willem de Bruijn <willemb@google.com> | 2019-02-15 12:15:47 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-27 10:09:01 +0100 |
| commit | e93384b12443c9bb6830b56b7d299beed432b865 (patch) | |
| tree | 1388263492656fbb8eb3db021836ed9084aed4b6 | |
| parent | 311722240ca62363ef8c9f37d50835b9faab3a31 (diff) | |
| download | linux-stable-e93384b12443c9bb6830b56b7d299beed432b865.tar.gz linux-stable-e93384b12443c9bb6830b56b7d299beed432b865.tar.bz2 linux-stable-e93384b12443c9bb6830b56b7d299beed432b865.zip | |
net: validate untrusted gso packets without csum offload
commit d5be7f632bad0f489879eed0ff4b99bd7fe0b74c upstream.
Syzkaller again found a path to a kernel crash through bad gso input.
By building an excessively large packet to cause an skb field to wrap.
If VIRTIO_NET_HDR_F_NEEDS_CSUM was set this would have been dropped in
skb_partial_csum_set.
GSO packets that do not set checksum offload are suspicious and rare.
Most callers of virtio_net_hdr_to_skb already pass them to
skb_probe_transport_header.
Move that test forward, change it to detect parse failure and drop
packets on failure as those cleary are not one of the legitimate
VIRTIO_NET_HDR_GSO types.
Fixes: bfd5f4a3d605 ("packet: Add GSO/csum offload support.")
Fixes: f43798c27684 ("tun: Allow GSO using virtio_net_hdr")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/skbuff.h | 2 | ||||
| -rw-r--r-- | include/linux/virtio_net.h | 9 |
2 files changed, 10 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 5d69e208e8d9..a404d475acee 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2392,7 +2392,7 @@ static inline void skb_probe_transport_header(struct sk_buff *skb, if (skb_flow_dissect_flow_keys_basic(skb, &keys, NULL, 0, 0, 0, 0)) skb_set_transport_header(skb, keys.control.thoff); - else + else if (offset_hint >= 0) skb_set_transport_header(skb, offset_hint); } diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h index cb462f9ab7dd..71f2394abbf7 100644 --- a/include/linux/virtio_net.h +++ b/include/linux/virtio_net.h @@ -57,6 +57,15 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb, if (!skb_partial_csum_set(skb, start, off)) return -EINVAL; + } else { + /* gso packets without NEEDS_CSUM do not set transport_offset. + * probe and drop if does not match one of the above types. + */ + if (gso_type) { + skb_probe_transport_header(skb, -1); + if (!skb_transport_header_was_set(skb)) + return -EINVAL; + } } if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) { |