[PATCH net-next v2 3/4] net: hsr: require valid EOT supervision TLV

[luka.gejak@linux.dev]

From: Luka Gejak <luka.gejak@linux.dev>

Supervision frames are only valid if terminated with a zero-length EOT
TLV. The current check fails to reject non-EOT entries as the terminal
TLV, potentially allowing malformed supervision traffic.

Fix this by strictly requiring the terminal TLV to be HSR_TLV_EOT
with a length of zero.

Reviewed-by: Felix Maurer <fmaurer@redhat.com>
Signed-off-by: Luka Gejak <luka.gejak@linux.dev>
---
 net/hsr/hsr_forward.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
index aefc9b6936ba..d26c7d0e8109 100644
--- a/net/hsr/hsr_forward.c
+++ b/net/hsr/hsr_forward.c
@@ -110,7 +110,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
 	}
 
 	/* end of tlvs must follow at the end */
-	if (hsr_sup_tlv->HSR_TLV_type == HSR_TLV_EOT &&
+	if (hsr_sup_tlv->HSR_TLV_type != HSR_TLV_EOT ||
 	    hsr_sup_tlv->HSR_TLV_length != 0)
 		return false;
 
-- 
2.53.0