Subject: [PATCH AUTOSEL 5.10 066/116] bpf: Do not WARN in bpf_warn_invalid_xdp_action()

From: Sasha Levin <[email-masked]>
Date: Mon, 17 Jan 2022 21:39:17 -0500

From: Paolo Abeni <[email-masked]>

[ 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 <[email-masked]>
Signed-off-by: Daniel Borkmann <[email-masked]>
Acked-by: Toke Høiland-Jørgensen <[email-masked]>
Link: https://lore.kernel.org/bpf/[email-masked]
Signed-off-by: Sasha Levin <[email-masked]>
---
 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 abd58dce49bbc..578b0bc78ac10 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -7919,9 +7919,9 @@ 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