linux-stable.git/net/netfilter/nf_queue.c, branch v5.10.260

netfilter: nf_queue: hold bridge skb->dev while queued

2026-06-19T11:21:45+00:00

[ Upstream commit e196115ec330a18de415bdb9f5071aa9f08e53ce ]

br_pass_frame_up() rewrites skb->dev from the ingress port to the bridge
master before queueing bridge LOCAL_IN packets. NFQUEUE only holds
references on state.in/out and bridge physdevs, so a queued bridge
packet can retain a freed bridge master in skb->dev until reinjection.

When the verdict is reinjected later, br_netif_receive_skb() re-enters
the receive path with skb->dev still pointing at the freed bridge master,
triggering a use-after-free.

Store skb->dev in the queue entry, hold a reference on it for the queue
lifetime, and use the saved device when dropping queued packets during
NETDEV_DOWN handling.

Fixes: ac2863445686 ("netfilter: bridge: add nf_afinfo to enable queuing to userspace")
Cc: stable@kernel.org
Reported-by: Yuan Tan 
Reported-by: Yifan Wu 
Reported-by: Juefei Pu 
Reported-by: Xin Liu 
Signed-off-by: Haoze Xie 
Signed-off-by: Ren Wei 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

net: Remove redundant if statements

2026-06-19T11:21:45+00:00

[ Upstream commit 1160dfa178eb848327e9dec39960a735f4dc1685 ]

The 'if (dev)' statement already move into dev_{put , hold}, so remove
redundant if statements.

Signed-off-by: Yajun Deng 
Signed-off-by: David S. Miller 
Stable-dep-of: e196115ec330 ("netfilter: nf_queue: hold bridge skb->dev while queued")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_queue: handle socket prefetch

2022-03-08T18:09:33+00:00

commit 3b836da4081fa585cf6c392f62557496f2cb0efe upstream.

In case someone combines bpf socket assign and nf_queue, then we will
queue an skb who references a struct sock that did not have its
reference count incremented.

As we leave rcu protection, there is no guarantee that skb->sk is still
valid.

For refcount-less skb->sk case, try to increment the reference count
and then override the destructor.

In case of failure we have two choices: orphan the skb and 'delete'
preselect or let nf_queue() drop the packet.

Do the latter, it should not happen during normal operation.

Fixes: cf7fbe660f2d ("bpf: Add socket assign support")
Acked-by: Joe Stringer 
Signed-off-by: Florian Westphal 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_queue: fix possible use-after-free

2022-03-08T18:09:33+00:00

commit c3873070247d9e3c7a6b0cf9bf9b45e8018427b1 upstream.

Eric Dumazet says:
  The sock_hold() side seems suspect, because there is no guarantee
  that sk_refcnt is not already 0.

On failure, we cannot queue the packet and need to indicate an
error.  The packet will be dropped by the caller.

v2: split skb prefetch hunk into separate change

Fixes: 271b72c7fa82c ("udp: RCU handling for Unicast packets.")
Reported-by: Eric Dumazet 
Reviewed-by: Eric Dumazet 
Signed-off-by: Florian Westphal 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_queue: don't assume sk is full socket

2022-03-08T18:09:33+00:00

commit 747670fd9a2d1b7774030dba65ca022ba442ce71 upstream.

There is no guarantee that state->sk refers to a full socket.

If refcount transitions to 0, sock_put calls sk_free which then ends up
with garbage fields.

I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable
debug work and pointing out state->sk oddities.

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Tested-by: Oleksandr Natalenko 
Signed-off-by: Florian Westphal 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_queue: prefer nf_queue_entry_free

2020-03-29T14:28:29+00:00

Instead of dropping refs+kfree, use the helper added in previous patch.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: nf_queue: do not release refcouts until nf_reinject is done

2020-03-29T14:28:29+00:00

nf_queue is problematic when another NF_QUEUE invocation happens
from nf_reinject().

1. nf_queue is invoked, increments state->sk refcount.
2. skb is queued, waiting for verdict.
3. sk is closed/released.
3. verdict comes back, nf_reinject is called.
4. nf_reinject drops the reference -- refcount can now drop to 0

Instead of get_ref/release_ref pattern, we need to nest the get_ref calls:
    get_ref
       get_ref
       release_ref
     release_ref

So that when we invoke the next processing stage (another netfilter
or the okfn()), we hold at least one reference count on the
devices/socket.

After previous patch, it is now safe to put the entry even after okfn()
has potentially free'd the skb.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: nf_queue: place bridge physports into queue_entry struct

2020-03-29T14:28:29+00:00

The refcount is done via entry->skb, which does work fine.
Major problem: When putting the refcount of the bridge ports, we
must always put the references while the skb is still around.

However, we will need to put the references after okfn() to avoid
a possible 1 -> 0 -> 1 refcount transition, so we cannot use the
skb pointer anymore.

Place the physports in the queue entry structure instead to allow
for refcounting changes in the next patch.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: nf_queue: make nf_queue_entry_release_refs static

2020-03-29T14:28:29+00:00

This is a preparation patch, no logical changes.
Move free_entry into core and rename it to something more sensible.

Will ease followup patches which will complicate the refcount handling.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: nf_queue: enqueue skbs with NULL dst

2019-12-07T18:53:00+00:00

Bridge packets that are forwarded have skb->dst == NULL and get
dropped by the check introduced by
b60a77386b1d4868f72f6353d35dabe5fbe981f2 (net: make skb_dst_force
return true when dst is refcounted).

To fix this we check skb_dst() before skb_dst_force(), so we don't
drop skb packet with dst == NULL. This holds also for skb at the
PRE_ROUTING hook so we remove the second check.

Fixes: b60a77386b1d ("net: make skb_dst_force return true when dst is refcounted")
Signed-off-by: Marco Oliverio 
Signed-off-by: Rocco Folino 
Acked-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso