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vxlan: Remove synchronize_net() in vxlan_sock_release().

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Initially, a dedicated workqueue was used to defer calling
udp_tunnel_sock_release(vxlan_sock->sock) and kfree(vxlan_sock).

Later, commit 0412bd931f ("vxlan: synchronously and race-free
destruction of vxlan sockets") removed the workqueue and instead
invoked these two functions immediately after synchronize_net().

This was intended to prevent UAF of the UDP socket in the fast path.

( Note that the "nondeterministic behaviour" mentioned in that
  commit was not addressed, as another thread not waiting RCU gp
  still sees the same behaviour. )

However, a week prior to that change, commit ca065d0cf8 ("udp:
no longer use SLAB_DESTROY_BY_RCU") had already moved UDP socket
freeing to after the RCU grace period.  This made the synchronize_net()
in vxlan_sock_release() completely redundant.

Since vxlan_sock now uses kfree_rcu() and is invoked after
udp_tunnel_sock_release(), vxlan_sock is guaranteed to be freed
either at the same time or after the UDP socket is released,
following the RCU grace period.

Let's remove the redundant synchronize_net() in vxlan_sock_release().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260518050726.318824-2-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2026-05-18 05:07:08 +00:00 committed by Jakub Kicinski
parent 25ae123db1
commit 425e30577f
1 changed files with 0 additions and 1 deletions
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1
drivers/net/vxlan/vxlan_core.c
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@ -1515,7 +1515,6 @@ static void vxlan_sock_release(struct vxlan_dev *vxlan)
#endif
RCU_INIT_POINTER(vxlan->vn4_sock, NULL);
synchronize_net();
if (vxlan->cfg.flags & VXLAN_F_VNIFILTER)
vxlan_vs_del_vnigrp(vxlan);