From 7bc78fb892e5e4b324204cc493876ec5109d0b9b Mon Sep 17 00:00:00 2001
From: Kazu Yamamoto <kazu@iij.ad.jp>
Date: Fri, 20 Dec 2024 16:41:27 +0900
Subject: [PATCH] don't allow tail garbage in client hello

---
 tls/Network/TLS/Packet.hs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/tls/Network/TLS/Packet.hs b/tls/Network/TLS/Packet.hs
index 096974584..7e79501e3 100644
--- a/tls/Network/TLS/Packet.hs
+++ b/tls/Network/TLS/Packet.hs
@@ -172,10 +172,9 @@ decodeClientHello = do
     exts <-
         if r > 0
             then fromIntegral <$> getWord16 >>= getExtensions
-            else do
-                rest <- remaining
-                _ <- getBytes rest
-                return []
+            else return []
+    r1 <- remaining
+    when (r1 /= 0) $ fail "Client hello"
     let ch = CH session ciphers exts
     return $ ClientHello ver random compressions ch