From af0fd013a16e3d858642a420104e0618c90e7fae Mon Sep 17 00:00:00 2001
From: Josh Holtrop <josh@wolfssl.com>
Date: Tue, 20 Jan 2026 08:14:02 -0500
Subject: [PATCH] HMAC-BLAKE2b: avoid coverity complaints about accessing x_key
 out of range

---
 wolfcrypt/src/blake2b.c | 8 ++++++--
 wolfcrypt/src/blake2s.c | 8 ++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/wolfcrypt/src/blake2b.c b/wolfcrypt/src/blake2b.c
index 7aab2e40f..37acb9744 100644
--- a/wolfcrypt/src/blake2b.c
+++ b/wolfcrypt/src/blake2b.c
@@ -534,7 +534,9 @@ int wc_Blake2bHmacInit(Blake2b* b2b, const byte* key, size_t key_len)
             ret = wc_Blake2bFinal(b2b, x_key, 0);
     } else {
         XMEMCPY(x_key, key, key_len);
-        XMEMSET(x_key + key_len, 0, BLAKE2B_BLOCKBYTES - key_len);
+        if (key_len < BLAKE2B_BLOCKBYTES) {
+            XMEMSET(x_key + key_len, 0, BLAKE2B_BLOCKBYTES - key_len);
+        }
     }
 
     if (ret == 0) {
@@ -581,7 +583,9 @@ int wc_Blake2bHmacFinal(Blake2b* b2b, const byte* key, size_t key_len,
             ret = wc_Blake2bFinal(b2b, x_key, 0);
     } else {
         XMEMCPY(x_key, key, key_len);
-        XMEMSET(x_key + key_len, 0, BLAKE2B_BLOCKBYTES - key_len);
+        if (key_len < BLAKE2B_BLOCKBYTES) {
+            XMEMSET(x_key + key_len, 0, BLAKE2B_BLOCKBYTES - key_len);
+        }
     }
 
     if (ret == 0) {
diff --git a/wolfcrypt/src/blake2s.c b/wolfcrypt/src/blake2s.c
index 6f5d1d2e9..b38d12a93 100644
--- a/wolfcrypt/src/blake2s.c
+++ b/wolfcrypt/src/blake2s.c
@@ -528,7 +528,9 @@ int wc_Blake2sHmacInit(Blake2s* b2s, const byte* key, size_t key_len)
             ret = wc_Blake2sFinal(b2s, x_key, 0);
     } else {
         XMEMCPY(x_key, key, key_len);
-        XMEMSET(x_key + key_len, 0, BLAKE2S_BLOCKBYTES - key_len);
+        if (key_len < BLAKE2S_BLOCKBYTES) {
+            XMEMSET(x_key + key_len, 0, BLAKE2S_BLOCKBYTES - key_len);
+        }
     }
 
     if (ret == 0) {
@@ -575,7 +577,9 @@ int wc_Blake2sHmacFinal(Blake2s* b2s, const byte* key, size_t key_len,
             ret = wc_Blake2sFinal(b2s, x_key, 0);
     } else {
         XMEMCPY(x_key, key, key_len);
-        XMEMSET(x_key + key_len, 0, BLAKE2S_BLOCKBYTES - key_len);
+        if (key_len < BLAKE2S_BLOCKBYTES) {
+            XMEMSET(x_key + key_len, 0, BLAKE2S_BLOCKBYTES - key_len);
+        }
     }
 
     if (ret == 0) {