Re: [PATCH net] tun: drop batched packets while the device is down
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From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2026-10-27 14:13:29
Xiao Liang wrote:
tun_sendmsg() handles TUN_MSG_PTR batches from vhost-net by calling
tun_xdp_one() instead of tun_get_user(). But this path does not check
IFF_UP, allowing packets from a guest to be injected into the host
receive path while the device is administratively down.
Check IFF_UP in tun_xdp_one() before running XDP or building an skb.
Drop the packet when the device is down, matching tun_get_user().
Fixes: 043d222f93ab ("tuntap: accept an array of XDP buffs through sendmsg()")
Signed-off-by: Xiao Liang <redacted>Reviewed-by: Willem de Bruijn <willemb@google.com>