Adjust the implementation of strncpy_s() for Linux

This change:
- prevents writing memory out of the range of the destination buffer
- prevents calling strlen() with non-null terminated c-string
- corrects the logic, which validates passed range to proceed
when real length fits the destination buffer

Related-To: NEO-7264
Signed-off-by: Wrobel, Patryk <patryk.wrobel@intel.com>

level_zero/core/source/driver/driver_handle_imp.cpp

@@ -140,7 +140,7 @@ ze_result_t DriverHandleImp::getExtensionProperties(uint32_t *pCount,
     for (uint32_t i = 0; i < *pCount; i++) {
         auto extension = this->extensionsSupported[i];
         strncpy_s(pExtensionProperties[i].name, ZE_MAX_EXTENSION_NAME,
-                  extension.first.c_str(), extension.first.length() + 1);
+                  extension.first.c_str(), extension.first.length());
         pExtensionProperties[i].version = extension.second;
     }
 

level_zero/core/source/kernel/kernel_imp.cpp

@@ -474,9 +474,9 @@ ze_result_t KernelImp::getSourceAttributes(uint32_t *pSize, char **pString) {
     if (pString == nullptr) {
         *pSize = (uint32_t)desc.kernelMetadata.kernelLanguageAttributes.length() + 1;
     } else {
-        strncpy_s(*pString, desc.kernelMetadata.kernelLanguageAttributes.length() + 1,
+        strncpy_s(*pString, *pSize,
                   desc.kernelMetadata.kernelLanguageAttributes.c_str(),
-                  desc.kernelMetadata.kernelLanguageAttributes.length() + 1);
+                  desc.kernelMetadata.kernelLanguageAttributes.length());
     }
     return ZE_RESULT_SUCCESS;
 }
@@ -721,7 +721,8 @@ ze_result_t KernelImp::getKernelName(size_t *pSize, char *pName) {
 
     *pSize = std::min(*pSize, kernelNameSize);
     strncpy_s(pName, *pSize,
-              this->kernelImmData->getDescriptor().kernelMetadata.kernelName.c_str(), kernelNameSize);
+              this->kernelImmData->getDescriptor().kernelMetadata.kernelName.c_str(),
+              this->kernelImmData->getDescriptor().kernelMetadata.kernelName.size());
 
     return ZE_RESULT_SUCCESS;
 }

level_zero/tools/source/sysman/firmware/linux/os_firmware_imp.cpp

@@ -51,7 +51,7 @@ bool LinuxFirmwareImp::isFirmwareSupported(void) {
 
 void LinuxFirmwareImp::osGetFwProperties(zes_firmware_properties_t *pProperties) {
     if (ZE_RESULT_SUCCESS != getFirmwareVersion(osFwType, pProperties)) {
-        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, unknown.c_str(), ZES_STRING_PROPERTY_SIZE);
+        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, unknown.c_str(), ZES_STRING_PROPERTY_SIZE - 1);
     }
     pProperties->canControl = true; //Assuming that user has permission to flash the firmware
 }

level_zero/tools/source/sysman/firmware/linux/os_firmware_imp_helper.cpp

@@ -14,9 +14,9 @@ ze_result_t LinuxFirmwareImp::getFirmwareVersion(std::string fwType, zes_firmwar
     std::string fwVersion;
     ze_result_t result = pFwInterface->getFwVersion(fwType, fwVersion);
     if (ZE_RESULT_SUCCESS == result) {
-        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, fwVersion.c_str(), ZES_STRING_PROPERTY_SIZE);
+        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, fwVersion.c_str(), ZES_STRING_PROPERTY_SIZE - 1);
     }
     return result;
 }
 
-} // namespace L0
+} // namespace L0

level_zero/tools/source/sysman/firmware/linux/os_firmware_imp_helper_prelim.cpp

@@ -43,15 +43,15 @@ ze_result_t LinuxFirmwareImp::getFirmwareVersion(std::string fwType, zes_firmwar
             // not able to read PSC version from iaf.x
             return result;
         }
-        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, pscVersion.c_str(), ZES_STRING_PROPERTY_SIZE);
+        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, pscVersion.c_str(), ZES_STRING_PROPERTY_SIZE - 1);
         return result;
     }
     ze_result_t result = pFwInterface->getFwVersion(fwType, fwVersion);
     if (result == ZE_RESULT_SUCCESS) {
-        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, fwVersion.c_str(), ZES_STRING_PROPERTY_SIZE);
+        strncpy_s(static_cast<char *>(pProperties->version), ZES_STRING_PROPERTY_SIZE, fwVersion.c_str(), ZES_STRING_PROPERTY_SIZE - 1);
     }
 
     return result;
 }
 
-} // namespace L0
+} // namespace L0

opencl/test/unit_test/program/printf_helper_tests.cpp

@@ -169,7 +169,7 @@ TEST_P(PrintfInt8Test, GivenFormatContainingIntWhenPrintingThenValueIsInserted)
     char referenceOutput[maxPrintfOutputLength];
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     snprintf(referenceOutput, sizeof(referenceOutput), input.format.c_str(), input.value);
 
@@ -209,7 +209,7 @@ TEST_P(PrintfInt32Test, GivenFormatContainingIntWhenPrintingThenValueIsInserted)
     char referenceOutput[maxPrintfOutputLength];
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     snprintf(referenceOutput, sizeof(referenceOutput), input.format.c_str(), input.value);
 
@@ -250,7 +250,7 @@ TEST_P(PrintfUint32Test, GivenFormatContainingUintWhenPrintingThenValueIsInserte
     char referenceOutput[maxPrintfOutputLength];
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     snprintf(referenceOutput, sizeof(referenceOutput), input.format.c_str(), input.value);
 
@@ -267,7 +267,7 @@ TEST_P(PrintfUint32Test, GivenBufferSizeGreaterThanPrintBufferWhenPrintingThenBu
 
     char referenceOutput[maxPrintfOutputLength] = "";
     char actualOutput[maxPrintfOutputLength] = "";
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ(referenceOutput, actualOutput);
 }
@@ -302,7 +302,7 @@ TEST_P(PrintfFloatTest, GivenFormatContainingFloatWhenPrintingThenValueIsInserte
     char referenceOutput[maxPrintfOutputLength];
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     snprintf(referenceOutput, sizeof(referenceOutput), input.format.c_str(), input.value);
 
@@ -345,7 +345,7 @@ TEST_P(PrintfDoubleToFloatTest, GivenFormatContainingFloatAndDoubleWhenPrintingT
     char referenceOutput[maxPrintfOutputLength];
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     snprintf(referenceOutput, sizeof(referenceOutput), input.format.c_str(), input.value);
 
@@ -390,7 +390,7 @@ TEST_P(PrintfDoubleTest, GivenFormatContainingDoubleWhenPrintingThenValueIsInser
     char referenceOutput[maxPrintfOutputLength];
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     if (input.format[input.format.length() - 1] == 'F')
         input.format[input.format.length() - 1] = 'f';
@@ -420,7 +420,7 @@ TEST_P(PrintfSpecialTest, GivenFormatContainingDoublePercentageWhenPrintingThenV
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ(input.second.c_str(), actualOutput);
 }
@@ -450,7 +450,7 @@ TEST_P(PrintfNoArgumentsTest, GivenNoArgumentsWhenPrintingThenCharsAreEscaped) {
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ(input.second.c_str(), actualOutput);
 }
@@ -478,7 +478,7 @@ TEST_P(PrintfStringTest, GivenFormatContainingStringWhenPrintingThenValueIsInser
     char referenceOutput[maxPrintfOutputLength];
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     snprintf(referenceOutput, sizeof(referenceOutput), input.format.c_str(), input.value.c_str());
 
@@ -499,7 +499,7 @@ TEST_F(PrintFormatterTest, GivenLongStringValueWhenPrintedThenFullStringIsPrinte
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ(testedLongString, actualOutput);
 }
@@ -517,7 +517,7 @@ TEST_F(PrintFormatterTest, GivenStringSpecifierWhenLongStringIsPassedAsValueThen
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ(testedLongString, actualOutput);
 }
@@ -533,7 +533,7 @@ TEST_F(PrintFormatterTest, GivenTooLongStringWhenPrintedThenOutputIsTruncated) {
     std::unique_ptr<char[]> actualOutput(new char[PrintFormatter::maxSinglePrintStringLength + 1024]);
 
     printFormatter->printKernelOutput([&actualOutput](char *str) { 
-        size_t length = strnlen_s(str, PrintFormatter::maxSinglePrintStringLength + 1024);
+        size_t length = strnlen_s(str, PrintFormatter::maxSinglePrintStringLength + 1023);
         strncpy_s(actualOutput.get(), PrintFormatter::maxSinglePrintStringLength + 1024, str, length); });
 
     auto testedLength = strnlen_s(testedLongString.get(), PrintFormatter::maxSinglePrintStringLength + 1024);
@@ -550,7 +550,7 @@ TEST_F(PrintFormatterTest, GivenNullTokenWhenPrintingThenNullIsInserted) {
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("(null)", actualOutput);
 }
@@ -572,7 +572,7 @@ TEST_F(PrintFormatterTest, GivenVector2WhenPrintingThenAllValuesAreInserted) {
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2", actualOutput);
 }
@@ -593,7 +593,7 @@ TEST_F(PrintFormatterTest, GivenVector4WhenPrintingThenAllValuesAreInserted) {
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2,3,4", actualOutput);
 }
@@ -614,7 +614,7 @@ TEST_F(PrintFormatterTest, GivenVector8WhenPrintingThenAllValuesAreInserted) {
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2,3,4,5,6,7,8", actualOutput);
 }
@@ -635,7 +635,7 @@ TEST_F(PrintFormatterTest, GivenVector16WhenPrintingThenAllValuesAreInserted) {
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16", actualOutput);
 }
@@ -656,7 +656,7 @@ TEST_F(PrintFormatterTest, GivenVectorOfBytesWhenPrintingThenAllValuesAreInserte
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2", actualOutput);
 }
@@ -676,7 +676,7 @@ TEST_F(PrintFormatterTest, GivenVectorOfShortsWhenPrintingThenAllValuesAreInsert
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2", actualOutput);
 }
@@ -696,7 +696,7 @@ TEST_F(PrintFormatterTest, GivenVectorOfIntsWhenPrintingThenAllValuesAreInserted
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2", actualOutput);
 }
@@ -716,7 +716,7 @@ TEST_F(PrintFormatterTest, GivenSpecialVectorWhenPrintingThenAllValuesAreInserte
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2", actualOutput);
 }
@@ -735,7 +735,7 @@ TEST_F(PrintFormatterTest, GivenVectorOfLongsWhenPrintingThenAllValuesAreInserte
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2", actualOutput);
 }
@@ -755,7 +755,7 @@ TEST_F(PrintFormatterTest, GivenVectorOfFloatsWhenPrintingThenAllValuesAreInsert
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1.000000,2.000000", actualOutput);
 }
@@ -775,7 +775,7 @@ TEST_F(PrintFormatterTest, GivenVectorOfDoublesWhenPrintingThenAllValuesAreInser
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1.000000,2.000000", actualOutput);
 }
@@ -801,7 +801,7 @@ TEST_F(PrintFormatterTest, GivenPointerWhenPrintingThenValueIsInserted) {
 
     snprintf(referenceOutput, sizeof(referenceOutput), "%p", reinterpret_cast<void *>(&temp));
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ(referenceOutput, actualOutput);
 }
@@ -829,7 +829,7 @@ TEST_F(PrintFormatterTest, GivenPointerWith32BitKernelWhenPrintingThen32BitPoint
 
     snprintf(referenceOutput, sizeof(referenceOutput), "%p", pointer);
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ(referenceOutput, actualOutput);
 }
@@ -866,7 +866,7 @@ TEST_F(PrintFormatterTest, Given2ByteVectorsWhenPrintingThenDataBufferParsedProp
 
     char actualOutput[maxPrintfOutputLength];
 
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
 
     EXPECT_STREQ("1,2,3,4 1,2,3,4", actualOutput);
 }
@@ -874,7 +874,7 @@ TEST_F(PrintFormatterTest, Given2ByteVectorsWhenPrintingThenDataBufferParsedProp
 TEST_F(PrintFormatterTest, GivenEmptyBufferWhenPrintingThenFailSafely) {
     char actualOutput[maxPrintfOutputLength];
     actualOutput[0] = 0;
-    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&actualOutput](char *str) { strncpy_s(actualOutput, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
     EXPECT_STREQ("", actualOutput);
 }
 
@@ -884,7 +884,7 @@ TEST_F(PrintFormatterTest, GivenNoStringMapAndBufferWithFormatStringThenItIsPrin
     storeData(formatString);
 
     char output[maxPrintfOutputLength];
-    printFormatter->printKernelOutput([&output](char *str) { strncpy_s(output, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&output](char *str) { strncpy_s(output, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
     EXPECT_STREQ(formatString, output);
 }
 
@@ -902,7 +902,7 @@ TEST_F(PrintFormatterTest, GivenNoStringMapAndBufferWithFormatStringAnd2StringsT
 
     const char *expectedOutput = "str1 str2";
     char output[maxPrintfOutputLength];
-    printFormatter->printKernelOutput([&output](char *str) { strncpy_s(output, maxPrintfOutputLength, str, maxPrintfOutputLength); });
+    printFormatter->printKernelOutput([&output](char *str) { strncpy_s(output, maxPrintfOutputLength, str, maxPrintfOutputLength - 1); });
     EXPECT_STREQ(expectedOutput, output);
 }
 

shared/source/helpers/string.h

@@ -31,28 +31,6 @@ inline int strcpy_s(char *dst, size_t dstSize, const char *src) { // NOLINT(read
     return 0;
 }
 
-inline int strncpy_s(char *dst, size_t numberOfElements, const char *src, size_t count) { // NOLINT(readability-identifier-naming)
-    if ((dst == nullptr) || (src == nullptr)) {
-        return -EINVAL;
-    }
-    if (numberOfElements < count) {
-        return -ERANGE;
-    }
-
-    size_t length = strlen(src);
-    if (length > count) {
-        length = count;
-    }
-    memcpy(dst, src, length);
-
-    if (length < numberOfElements) {
-        numberOfElements = length;
-    }
-    dst[numberOfElements] = '\0';
-
-    return 0;
-}
-
 inline size_t strnlen_s(const char *str, size_t count) { // NOLINT(readability-identifier-naming)
     if (str == nullptr) {
         return 0;
@@ -66,6 +44,22 @@ inline size_t strnlen_s(const char *str, size_t count) { // NOLINT(readability-i
     return count;
 }
 
+inline int strncpy_s(char *dst, size_t numberOfElements, const char *src, size_t count) { // NOLINT(readability-identifier-naming)
+    if ((dst == nullptr) || (src == nullptr)) {
+        return -EINVAL;
+    }
+
+    size_t length = strnlen_s(src, count);
+    if (numberOfElements <= count && numberOfElements <= length) {
+        return -ERANGE;
+    }
+
+    memcpy(dst, src, length);
+    dst[length] = '\0';
+
+    return 0;
+}
+
 inline int memcpy_s(void *dst, size_t destSize, const void *src, size_t count) { // NOLINT(readability-identifier-naming)
     if ((dst == nullptr) || (src == nullptr)) {
         return -EINVAL;

shared/test/unit_test/helpers/string_tests.cpp

@@ -27,7 +27,7 @@ TEST(StringHelpers, GivenParamsWhenUsingStrncpyThenReturnIsCorrect) {
     ret = strncpy_s(dst, 1024, nullptr, 1024);
     EXPECT_EQ(ret, -EINVAL);
 
-    ret = strncpy_s(dst, 512, src, 1024);
+    ret = strncpy_s(dst, 10, src, 1024);
     EXPECT_EQ(ret, -ERANGE);
 
     memset(dst, 0, sizeof(dst));
@@ -37,19 +37,41 @@ TEST(StringHelpers, GivenParamsWhenUsingStrncpyThenReturnIsCorrect) {
     for (size_t i = strlen(src) / 2; i < sizeof(dst); i++)
         EXPECT_EQ(0, dst[i]);
 
-    memset(dst, 0, sizeof(dst));
-    ret = strncpy_s(dst, strlen(src) / 2, src, strlen(src) / 2);
-    EXPECT_EQ(ret, 0);
-    EXPECT_EQ(0, memcmp(dst, src, strlen(src) / 2));
-    for (size_t i = strlen(src) / 2; i < sizeof(dst); i++)
-        EXPECT_EQ(0, dst[i]);
+    ret = strncpy_s(dst, 1024, src, 1024);
+    ASSERT_EQ(0, ret);
 
-    strncpy_s(dst, 1024, src, 1024);
     EXPECT_EQ(0, memcmp(dst, src, strlen(src)));
     for (size_t i = strlen(src); i < sizeof(dst); i++)
         EXPECT_EQ(0, dst[i]);
 }
 
+TEST(StringHelpers, GivenCountGreaterEqualToNumberOfElementsThenReturnErangeAndSetFirstStringToNullTerminator) {
+    // strncpy_s() copies at most COUNT bytes and appends null-terminator at dst[COUNT].
+    // It means, that for given COUNT, at least COUNT+1 bytes are required in dst buffer.
+
+    const size_t firstWordLength = 9;
+    char src[] = "c-strings are serious business!";
+
+    char dst[firstWordLength] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'};
+    const auto ret = strncpy_s(dst, sizeof(dst), src, firstWordLength);
+
+    EXPECT_EQ(-ERANGE, ret);
+}
+
+TEST(StringHelpers, GivenNotNullTerminatedSourceThenCopyAtMostCountBytesAndAppendNulltermination) {
+    // If null-terminator is missing, then strncpy_s() copies COUNT bytes and stores it at dst[COUNT].
+
+    const size_t srcLength = 8;
+    char src[srcLength] = {'c', '-', 's', 't', 'r', 'i', 'n', 'g'};
+
+    const size_t nullterminatorLength = 1;
+    char dst[srcLength + nullterminatorLength] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'};
+    const auto ret = strncpy_s(dst, sizeof(dst), src, srcLength);
+
+    ASSERT_EQ(0, ret);
+    EXPECT_STREQ("c-string", dst);
+}
+
 TEST(StringHelpers, GivenParamsWhenUsingMemmoveThenReturnIsCorrect) {
     char dst[1024] = "";
     char src[1024] = "HelloWorld";