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    Subject[PATCH 4.19 51/57] net: geneve: check skb is large enough for IPv4/IPv6 header
    Date
    From: Phillip Potter <phil@philpotter.co.uk>

    [ Upstream commit 6628ddfec7580882f11fdc5c194a8ea781fdadfa ]

    Check within geneve_xmit_skb/geneve6_xmit_skb that sk_buff structure
    is large enough to include IPv4 or IPv6 header, and reject if not. The
    geneve_xmit_skb portion and overall idea was contributed by Eric Dumazet.
    Fixes a KMSAN-found uninit-value bug reported by syzbot at:
    https://syzkaller.appspot.com/bug?id=abe95dc3e3e9667fc23b8d81f29ecad95c6f106f

    Suggested-by: Eric Dumazet <edumazet@google.com>
    Reported-by: syzbot+2e406a9ac75bb71d4b7a@syzkaller.appspotmail.com
    Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/geneve.c | 6 ++++++
    1 file changed, 6 insertions(+)

    diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
    index 2e2afc824a6a..ce6fecf421f8 100644
    --- a/drivers/net/geneve.c
    +++ b/drivers/net/geneve.c
    @@ -839,6 +839,9 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
    __be16 df;
    int err;

    + if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
    + return -EINVAL;
    +
    sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
    rt = geneve_get_v4_rt(skb, dev, gs4, &fl4, info,
    geneve->info.key.tp_dst, sport);
    @@ -882,6 +885,9 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
    __be16 sport;
    int err;

    + if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
    + return -EINVAL;
    +
    sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
    dst = geneve_get_v6_dst(skb, dev, gs6, &fl6, info,
    geneve->info.key.tp_dst, sport);
    --
    2.30.2


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