Switch to SaturatingSubtract to guard against wrap on user parameters

1 files changed, 18 insertions, 20 deletions

diff --git a/blake2.cpp b/blake2.cpp
index 73cd4870..a97564a5 100644
--- a/blake2.cpp
+++ b/blake2.cpp
@@ -152,7 +152,6 @@ BLAKE2_ParameterBlock<false>::BLAKE2_ParameterBlock(size_t digestLen, size_t key
         const byte* saltStr, size_t saltLen,

         const byte* personalizationStr, size_t personalizationLen)

 {

-    // Avoid Coverity finding SIZEOF_MISMATCH/suspicious_sizeof

     digestLength = (byte)digestLen;

     keyLength = (byte)keyLen;

     fanout = depth = 1;

@@ -164,8 +163,8 @@ BLAKE2_ParameterBlock<false>::BLAKE2_ParameterBlock(size_t digestLen, size_t key
     if (saltStr && saltLen)

     {

         memcpy_s(salt, COUNTOF(salt), saltStr, saltLen);

-        const size_t rem = COUNTOF(salt) - saltLen;

-        const size_t off = COUNTOF(salt) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(salt), saltLen);

+        size_t off = COUNTOF(salt) - rem;

         if (rem)

             std::memset(salt+off, 0x00, rem);

     }

@@ -177,8 +176,8 @@ BLAKE2_ParameterBlock<false>::BLAKE2_ParameterBlock(size_t digestLen, size_t key
     if (personalizationStr && personalizationLen)

     {

         memcpy_s(personalization, COUNTOF(personalization), personalizationStr, personalizationLen);

-        const size_t rem = COUNTOF(personalization) - personalizationLen;

-        const size_t off = COUNTOF(personalization) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(personalization), personalizationLen);

+        size_t off = COUNTOF(personalization) - rem;

         if (rem)

             std::memset(personalization+off, 0x00, rem);

     }

@@ -192,7 +191,6 @@ BLAKE2_ParameterBlock<true>::BLAKE2_ParameterBlock(size_t digestLen, size_t keyL
         const byte* saltStr, size_t saltLen,

         const byte* personalizationStr, size_t personalizationLen)

 {

-    // Avoid Coverity finding SIZEOF_MISMATCH/suspicious_sizeof

     digestLength = (byte)digestLen;

     keyLength = (byte)keyLen;

     fanout = depth = 1;

@@ -205,8 +203,8 @@ BLAKE2_ParameterBlock<true>::BLAKE2_ParameterBlock(size_t digestLen, size_t keyL
     if (saltStr && saltLen)

     {

         memcpy_s(salt, COUNTOF(salt), saltStr, saltLen);

-        const size_t rem = COUNTOF(salt) - saltLen;

-        const size_t off = COUNTOF(salt) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(salt), saltLen);

+        size_t off = COUNTOF(salt) - rem;

         if (rem)

             std::memset(salt+off, 0x00, rem);

     }

@@ -218,8 +216,8 @@ BLAKE2_ParameterBlock<true>::BLAKE2_ParameterBlock(size_t digestLen, size_t keyL
     if (personalizationStr && personalizationLen)

     {

         memcpy_s(personalization, COUNTOF(personalization), personalizationStr, personalizationLen);

-        const size_t rem = COUNTOF(personalization) - personalizationLen;

-        const size_t off = COUNTOF(personalization) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(personalization), personalizationLen);

+        size_t off = COUNTOF(personalization) - rem;

         if (rem)

             std::memset(personalization+off, 0x00, rem);

     }

@@ -237,7 +235,7 @@ void BLAKE2_Base<word32, false>::UncheckedSetKey(const byte *key, unsigned int l
         AlignedSecByteBlock temp(BLOCKSIZE);

         memcpy_s(temp, BLOCKSIZE, key, length);

 

-        const size_t rem = BLOCKSIZE - length;

+        size_t rem = SaturatingSubtract(BLOCKSIZE, length);

         if (rem)

             std::memset(temp+length, 0x00, rem);

 

@@ -261,8 +259,8 @@ void BLAKE2_Base<word32, false>::UncheckedSetKey(const byte *key, unsigned int l
     if (params.GetValue(Name::Salt(), t) && t.begin() && t.size())

     {

         memcpy_s(block.salt, COUNTOF(block.salt), t.begin(), t.size());

-        const size_t rem = COUNTOF(block.salt) - t.size();

-        const size_t off = COUNTOF(block.salt) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(block.salt), t.size());

+        size_t off = COUNTOF(block.salt) - rem;

         if (rem)

             std::memset(block.salt+off, 0x00, rem);

     }

@@ -274,8 +272,8 @@ void BLAKE2_Base<word32, false>::UncheckedSetKey(const byte *key, unsigned int l
     if (params.GetValue(Name::Personalization(), t) && t.begin() && t.size())

     {

         memcpy_s(block.personalization, COUNTOF(block.personalization), t.begin(), t.size());

-        const size_t rem = COUNTOF(block.personalization) - t.size();

-        const size_t off = COUNTOF(block.personalization) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(block.personalization), t.size());

+        size_t off = COUNTOF(block.personalization) - rem;

         if (rem)

             std::memset(block.personalization+off, 0x00, rem);

     }

@@ -293,7 +291,7 @@ void BLAKE2_Base<word64, true>::UncheckedSetKey(const byte *key, unsigned int le
         AlignedSecByteBlock temp(BLOCKSIZE);

         memcpy_s(temp, BLOCKSIZE, key, length);

 

-        const size_t rem = BLOCKSIZE - length;

+        size_t rem = SaturatingSubtract(BLOCKSIZE, length);

         if (rem)

             std::memset(temp+length, 0x00, rem);

 

@@ -318,8 +316,8 @@ void BLAKE2_Base<word64, true>::UncheckedSetKey(const byte *key, unsigned int le
     if (params.GetValue(Name::Salt(), t) && t.begin() && t.size())

     {

         memcpy_s(block.salt, COUNTOF(block.salt), t.begin(), t.size());

-        const size_t rem = COUNTOF(block.salt) - t.size();

-        const size_t off = COUNTOF(block.salt) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(block.salt), t.size());

+        size_t off = COUNTOF(block.salt) - rem;

         if (rem)

             std::memset(block.salt+off, 0x00, rem);

     }

@@ -331,8 +329,8 @@ void BLAKE2_Base<word64, true>::UncheckedSetKey(const byte *key, unsigned int le
     if (params.GetValue(Name::Personalization(), t) && t.begin() && t.size())

     {

         memcpy_s(block.personalization, COUNTOF(block.personalization), t.begin(), t.size());

-        const size_t rem = COUNTOF(block.personalization) - t.size();

-        const size_t off = COUNTOF(block.personalization) - rem;

+        size_t rem = SaturatingSubtract(COUNTOF(block.personalization), t.size());

+        size_t off = COUNTOF(block.personalization) - rem;

         if (rem)

             std::memset(block.personalization+off, 0x00, rem);

     }