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net/packet: fix a race in packet_set_ring() and packet_notifier()

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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 15fe076ede
("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: 1da177e4c3 ("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@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Quang Le 2025-08-01 13:54:16 -04:00 • committed by Jakub Kicinski
parent 5a40f8af2b
commit 01d3c8417b
1 changed files with 6 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

12
net/packet/af_packet.c
View file

@ -4573,10 +4573,10 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
spin_lock(&po->bind_lock);
was_running = packet_sock_flag(po, PACKET_SOCK_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();
@ -4608,10 +4608,10 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
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 */