Commit 75f7885d authored Nov 30, 2021 by Paolo Abeni Committed by Greg Kroah-Hartman Jan 27, 2022

bpf: Do not WARN in bpf_warn_invalid_xdp_action()



[ Upstream commit 2cbad989033bff0256675c38f96f5faab852af4b ]

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: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/016ceec56e4817ebb2a9e35ce794d5c917df572c.1638189075.git.pabeni@redhat.com


Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 086181b0

net/core/filter.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -6912,7 +6912,7 @@ 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);
		}