From 36198800a3e5a58aae6b4b141e5c8752d736e6f9 Mon Sep 17 00:00:00 2001
From: John Safranek <john@wolfssl.com>
Date: Tue, 23 Jun 2026 14:52:48 -0700
Subject: [PATCH] Strip trailing comma from peer name lists

- GetNameListRaw folded a trailing comma into the last name,
  so NameToId returned ID_UNKNOWN and negotiation failed.
- Trim one trailing comma up front, matching AlgoListSz.
- Add regression test for a KEX list with a trailing comma.

Issue: F-2478
---
 src/internal.c  |  5 +++++
 tests/regress.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/src/internal.c b/src/internal.c
index d4ebb91a..4f8b1401 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -4181,6 +4181,11 @@ static int GetNameListRaw(byte* idList, word32* idListSz,
         return WS_BAD_ARGUMENT;
     }
 
+    /* Adjust nameListSz for a trailing comma. */
+    if (nameListSz > 0 && nameList[nameListSz - 1] == ',') {
+        nameListSz--;
+    }
+
     /* Reject oversized name-lists to bound the per-token NameToId scan cost.
      * Applies to every list parsed here; the built-in canned lists are far
      * under these caps. */
diff --git a/tests/regress.c b/tests/regress.c
index 11cf806d..b0d2086e 100644
--- a/tests/regress.c
+++ b/tests/regress.c
@@ -2980,6 +2980,40 @@ static void TestKexInitNameListCaps(void)
     WFREE(list, NULL, DYNTYPE_STRING);
 }
 
+/* A peer name list may legally end with a trailing comma. GetNameListRaw
+ * used to fold that comma into the final name, yielding ID_UNKNOWN and a
+ * failed negotiation. Build a KEXINIT whose KEX list ends in a comma and
+ * assert the algorithm still negotiates. */
+static void TestKexInitTrailingComma(void)
+{
+    WOLFSSH_CTX* ctx;
+    WOLFSSH* ssh;
+    byte payload[512];
+    word32 payloadSz;
+    word32 idx = 0;
+
+    ctx = wolfSSH_CTX_new(WOLFSSH_ENDPOINT_SERVER, NULL);
+    AssertNotNull(ctx);
+    ssh = wolfSSH_new(ctx);
+    AssertNotNull(ssh);
+    AssertIntEQ(wolfSSH_SetAlgoListKex(ssh, FPF_KEX_GOOD), WS_SUCCESS);
+    AssertIntEQ(wolfSSH_SetAlgoListKey(ssh, FPF_KEY_GOOD), WS_SUCCESS);
+
+    /* KEX list carries a trailing comma. */
+    payloadSz = BuildKexInitPayload(ssh, FPF_KEX_GOOD ",", FPF_KEY_GOOD,
+            0, payload, (word32)sizeof(payload));
+
+    /* The tail (host key/send) errors on this bare ssh, but negotiation
+     * runs first and records the result in handshake->kexId. */
+    (void)wolfSSH_TestDoKexInit(ssh, payload, payloadSz, &idx);
+
+    AssertNotNull(ssh->handshake);
+    AssertIntEQ(ssh->handshake->kexId, ID_ECDH_SHA2_NISTP256);
+
+    wolfSSH_free(ssh);
+    wolfSSH_CTX_free(ctx);
+}
+
 #if !defined(WOLFSSH_NO_AES_CBC) && !defined(WOLFSSH_NO_AES_CTR) \
     && !defined(WOLFSSH_NO_HMAC_SHA1) && !defined(WOLFSSH_NO_HMAC_SHA2_256)
 static void TestIndependentAlgoNegotiation(void)
@@ -4391,6 +4425,7 @@ int main(int argc, char** argv)
     TestFirstPacketFollows();
     TestKexInitReservedNonZeroRejected();
     TestKexInitNameListCaps();
+    TestKexInitTrailingComma();
     TestDoKexInitRejectsWhenPeerIsKeying();
 #endif
 #if !defined(WOLFSSH_NO_ECDH_SHA2_NISTP256) && !defined(WOLFSSH_NO_RSA) \