5.4-stable review patch. If anyone has any objections, please let me know.
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From: Quang Le quanglex97@gmail.com
commit 01d3c8417b9c1b884a8a981a3b886da556512f36 upstream.
When packet_set_ring() releases po->bind_lock, another thread can run packet_notifier() and process an NETDEV_UP event.
This race and the fix are both similar to that of commit 15fe076edea7 ("net/packet: fix a race in packet_bind() and packet_notifier()").
There too the packet_notifier NETDEV_UP event managed to run while a po->bind_lock critical section had to be temporarily released. And the fix was similarly to temporarily set po->num to zero to keep the socket unhooked until the lock is retaken.
The po->bind_lock in packet_set_ring and packet_notifier precede the introduction of git history.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Quang Le quanglex97@gmail.com Signed-off-by: Willem de Bruijn willemb@google.com Link: https://patch.msgid.link/20250801175423.2970334-1-willemdebruijn.kernel@gmai... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/packet/af_packet.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
--- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -4504,10 +4504,10 @@ static int packet_set_ring(struct sock * spin_lock(&po->bind_lock); was_running = po->running; num = po->num; - if (was_running) { - WRITE_ONCE(po->num, 0); + WRITE_ONCE(po->num, 0); + if (was_running) __unregister_prot_hook(sk, false); - } + spin_unlock(&po->bind_lock);
synchronize_net(); @@ -4539,10 +4539,10 @@ static int packet_set_ring(struct sock * mutex_unlock(&po->pg_vec_lock);
spin_lock(&po->bind_lock); - if (was_running) { - WRITE_ONCE(po->num, num); + WRITE_ONCE(po->num, num); + if (was_running) register_prot_hook(sk); - } + spin_unlock(&po->bind_lock); if (pg_vec && (po->tp_version > TPACKET_V2)) { /* Because we don't support block-based V3 on tx-ring */