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Commit 9fc12023 authored by Lorenzo Bianconi's avatar Lorenzo Bianconi Committed by David S. Miller
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ipv4: remove BUG_ON() from fib_compute_spec_dst 



Remove BUG_ON() from fib_compute_spec_dst routine and check
in_dev pointer during flowi4 data structure initialization.
fib_compute_spec_dst routine can be run concurrently with device removal
where ip_ptr net_device pointer is set to NULL. This can happen
if userspace enables pkt info on UDP rx socket and the device
is removed while traffic is flowing

Fixes: 35ebf65e ("ipv4: Create and use fib_compute_spec_dst() helper")
Signed-off-by: default avatarLorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ab123fe0

net/ipv4/fib_frontend.c

+2 −2
Original line number Diff line number Diff line
@@ -292,19 +292,19 @@ __be32 fib_compute_spec_dst(struct sk_buff *skb) 
		return ip_hdr(skb)->daddr;



	in_dev = __in_dev_get_rcu(dev);

	BUG_ON(!in_dev);



	net = dev_net(dev);



	scope = RT_SCOPE_UNIVERSE;

	if (!ipv4_is_zeronet(ip_hdr(skb)->saddr)) {

		bool vmark = in_dev && IN_DEV_SRC_VMARK(in_dev);

		struct flowi4 fl4 = {

			.flowi4_iif = LOOPBACK_IFINDEX,

			.flowi4_oif = l3mdev_master_ifindex_rcu(dev),

			.daddr = ip_hdr(skb)->saddr,

			.flowi4_tos = RT_TOS(ip_hdr(skb)->tos),

			.flowi4_scope = scope,

			.flowi4_mark = IN_DEV_SRC_VMARK(in_dev) ? skb->mark : 0,

			.flowi4_mark = vmark ? skb->mark : 0,

		};

		if (!fib_lookup(net, &fl4, &res, 0))

			return FIB_RES_PREFSRC(net, res);