diff options
author | Eric Dumazet <edumazet@google.com> | 2024-09-24 18:02:57 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-10-17 16:11:21 +0300 |
commit | 2415f465730e48b6e38da1c7c097317bf5dd2d20 (patch) | |
tree | 871bf254f3d7ef393c711642032b2f4f121500a2 /net | |
parent | 939c88cbdc668dadd8cfa7a35d9066331239041c (diff) | |
download | linux-2415f465730e48b6e38da1c7c097317bf5dd2d20.tar.xz |
net: add more sanity checks to qdisc_pkt_len_init()
[ Upstream commit ab9a9a9e9647392a19e7a885b08000e89c86b535 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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 96e093e2206f..8a22ce15b7f5 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3795,10 +3795,14 @@ 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; } } |