diff options
| author | Eric Dumazet <edumazet@google.com> | 2024-09-24 15:02:57 +0000 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2024-10-01 11:47:05 +0200 |
| commit | ab9a9a9e9647392a19e7a885b08000e89c86b535 (patch) | |
| tree | a1459d6153629dc225628a0994b929b7251e227a /net | |
| parent | c20029db28399ecc50e556964eaba75c43b1e2f1 (diff) | |
net: add more sanity checks to qdisc_pkt_len_init()
One path takes care of SKB_GSO_DODGY, assuming
skb->len is bigger than hdr_len.
virtio_net_hdr_to_skb() does not fully dissect TCP headers,
it only make sure it is at least 20 bytes.
It is possible for an user to provide a malicious 'GSO' packet,
total length of 80 bytes.
- 20 bytes of IPv4 header
- 60 bytes TCP header
- a small gso_size like 8
virtio_net_hdr_to_skb() would declare this packet as a normal
GSO packet, because it would see 40 bytes of payload,
bigger than gso_size.
We need to make detect this case to not underflow
qdisc_skb_cb(skb)->pkt_len.
Fixes: 1def9238d4aa ("net_sched: more precise pkt_len computation")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/dev.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 7d3d34a3bdf5..ea5fbcd133ae 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3766,10 +3766,14 @@ static void qdisc_pkt_len_init(struct sk_buff *skb) hdr_len += sizeof(struct udphdr); } - if (shinfo->gso_type & SKB_GSO_DODGY) - gso_segs = DIV_ROUND_UP(skb->len - hdr_len, - shinfo->gso_size); + if (unlikely(shinfo->gso_type & SKB_GSO_DODGY)) { + int payload = skb->len - hdr_len; + /* Malicious packet. */ + if (payload <= 0) + return; + gso_segs = DIV_ROUND_UP(payload, shinfo->gso_size); + } qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len; } } |