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CVE-2024-49948
In the Linux kernel, the following vulnerability has been resolved:
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.
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