[PATCH 5.4 188/320] bpf: Do not WARN in bpf_warn_invalid_xdp_action()

Greg Kroah-Hartman
2022-01-24T19:41:04Z

From: Paolo Abeni <pabeni@redhat.com>

[ 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>
---
net/core/filter.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index b90c0b5a10112..92ce4d46f02e4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6912,9 +6912,9 @@ 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",
- act > act_max ? "Illegal" : "Driver unsupported",
- act);
+ pr_warn_once("%s XDP return value %u, expect packet loss!\n",
+ act > act_max ? "Illegal" : "Driver unsupported",
+ act);
}
EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action);

--
2.34.1