Commit 2cbad989 authored by Paolo Abeni's avatar Paolo Abeni Committed by Daniel Borkmann
Browse files

bpf: Do not WARN in bpf_warn_invalid_xdp_action() 



The WARN_ONCE() in bpf_warn_invalid_xdp_action() can be triggered by
any bugged program, and even attaching a correct program to a NIC
not supporting the given action.

The resulting splat, beyond polluting the logs, fouls automated tools:
e.g. a syzkaller reproducers using an XDP program returning an
unsupported action will never pass validation.

Replace the WARN_ONCE with a less intrusive pr_warn_once().

Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/016ceec56e4817ebb2a9e35ce794d5c917df572c.1638189075.git.pabeni@redhat.com
parent e94fac38

net/core/filter.c

+3 −3
Original line number Diff line number Diff line
@@ -8184,7 +8184,7 @@ void bpf_warn_invalid_xdp_action(u32 act) 
{

	const u32 act_max = XDP_REDIRECT;



	WARN_ONCE(1, "%s XDP return value %u, expect packet loss!\n",

	pr_warn_once("%s XDP return value %u, expect packet loss!\n",

		     act > act_max ? "Illegal" : "Driver unsupported",

		     act);

}