From f860f4bf81be9bd8d09607a83ac9e4eaf3a174ac Mon Sep 17 00:00:00 2001
From: Aidan Keefe <aidan.keefe@wolfssl.com>
Date: Wed, 2 Sep 2026 15:22:43 -0600
Subject: [PATCH] Added cheap bounds checking:

Check that the bottm 3 bits of any input size are 0.
---
 wolfcrypt/src/des3.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/wolfcrypt/src/des3.c b/wolfcrypt/src/des3.c
index f816a5fe96..39a7b5ee90 100644
--- a/wolfcrypt/src/des3.c
+++ b/wolfcrypt/src/des3.c
@@ -881,6 +881,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
         }
     #endif
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
         while (len > 0)
         {
             XMEMCPY(temp_block, in + offset, DES_BLOCK_SIZE);
@@ -926,6 +931,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
         }
     #endif
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
         while (len > 0)
         {
             XMEMCPY(temp_block, in + offset, DES_BLOCK_SIZE);
@@ -973,6 +983,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
         }
     #endif
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
         while (len > 0)
         {
             XMEMCPY(temp_block, in + offset, DES_BLOCK_SIZE);
@@ -1023,6 +1038,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
         }
     #endif
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
         while (len > 0)
         {
             XMEMCPY(temp_block, in + offset, DES_BLOCK_SIZE);
@@ -1073,6 +1093,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
         }
     #endif
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
         while (len > 0)
         {
             XMEMCPY(temp_block, in + offset, DES_BLOCK_SIZE);
@@ -1110,6 +1135,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
         }
     #endif
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
         while (len > 0)
         {
             XMEMCPY(temp_block, in + offset, DES_BLOCK_SIZE);
@@ -1149,6 +1179,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
             return MISSING_KEY;
         }
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
     #ifdef FREESCALE_MMCAU_CLASSIC
         if ((wc_ptr_t)out % WOLFSSL_MMCAU_ALIGNMENT) {
             WOLFSSL_MSG("Bad 3ede cau_des_encrypt alignment");
@@ -1199,6 +1234,11 @@ static WC_INLINE void wc_Stm32_CrypDesBlock(const byte* in, byte* out)
             return MISSING_KEY;
         }
 
+        if (sz & (DES_BLOCK_SIZE - 1)) {
+            WOLFSSL_MSG("Buffer length was not a multiple of DES block size");
+            return BAD_LENGTH_E;
+        }
+
     #ifdef FREESCALE_MMCAU_CLASSIC
         if ((wc_ptr_t)out % WOLFSSL_MMCAU_ALIGNMENT) {
             WOLFSSL_MSG("Bad 3ede cau_des_decrypt alignment");