AWSClient PutObject crashes when the body is empty and the checksum algorithm is MD5

[pcaswell]

Describe the bug

What platform/OS are you using?
Windows 10 64bit Professional

What compiler are you using? what version?
Microsoft (R) C/C++ Optimizing Compiler Version 19.16.27045 for x64

What's your CMake arguments?
cmake ../${AWS_SDK_BASENAME} -G "Visual Studio 15 2017 Win64"
-DENABLE_TESTING=OFF
-DENABLE_UNITY_BUILD=ON
-DSIMPLE_INSTALL=OFF
-DAUTORUN_UNIT_TESTS=OFF
-DCMAKE_INSTALL_PREFIX="${TOOLS_X64}/${AWS_SDK_BASENAME}"
-DCMAKE_PDB_OUTPUT_DIRECTORY="${TOOLS_X64}/${AWS_SDK_BASENAME}/bin/windows/intel64"
-DCPP_STANDARD=17
-DBUILD_ONLY="s3;dynamodb;lambda;iam;autoscaling;application-autoscaling;sts;monitoring"

Where ${AWS_SDK_BASENAME} = 1.9.280

Can you provide a TRACE level log? (sanitize any sensitive information)
Later if required.

I have recently upgraded our product from 1.6.25 to 1.9.280 (1.6.25 has been in production for over a year).

PutObjectRequest oRequest;
oRequest.SetBucket(toUTF8(sBucket));
oRequest.SetKey(toUTF8(oKey.value()));

auto oOutcome = mpClient->PutObject(oRequest);
if (oOutcome.IsSuccess())
{
            ....
}

The code above now crashes in the SDK in aws-sdk-cpp-1.9.280-build\aws-sdk-cpp-1.9.280\aws-cpp-sdk-core\source\utils\crypto\bcrypt\CryptoImpl.cpp, line 351 because the struct 'stream' is NULL. It's NULL I think because I haven't set a body on the request as I want to create a 0 byte object in S3. This means that in aws-sdk-cpp-1.9.280\aws-cpp-sdk-core\source\client\AWSClient.cpp line 710 the stream value being passed into this code is NULL:

httpRequest->SetHeaderValue(Http::CONTENT_MD5_HEADER, HashingUtils::Base64Encode(HashingUtils::CalculateMD5(*(request.GetBody()))));

Now it may be that I've missed something with the new SDK version. If so I'd appreciate a steer in the right direction.
Thanks in advance for the help.

Expected Behavior

This call should work if the input request has no body.
auto oOutcome = mpClient->PutObject(oRequest);

Current Behavior

Crashed.

Reproduction Steps

This code crashes (for me):

PutObjectRequest oRequest;
oRequest.SetBucket(toUTF8(sBucket));
oRequest.SetKey(toUTF8(oKey.value()));

auto oOutcome = mpClient->PutObject(oRequest);

Possible Solution

Handle the case where an MD5 checksum is trying to be computed for a 0 byte request body.

Additional Information/Context

No response

AWS CPP SDK version used

1.9.280

Compiler and Version used

Microsoft (R) C/C++ Optimizing Compiler Version 19.16.27045 for x64

Operating System and version

Windows 10 64bit Professional

[andreaszervas]

I got the same problem on linux os using:
AWS SDK version 1.9.258
compiler version: gcc (GCC) 8.3.1 20190311 (Red Hat 8.3.1-3)

[pcaswell]

I have avoided the crash by making this change to the AWSClient.cpp (line 708 to 175)

        else if (checksumAlgorithmName == "md5")
        {
            auto body = request.GetBody();
            if (body)
            {
                httpRequest->SetHeaderValue(Http::CONTENT_MD5_HEADER, HashingUtils::Base64Encode(HashingUtils::CalculateMD5(*body)));
            }
        }

Not sure if this is the right approach though.

[pepi55]

Same issue here on AmazonLinux 5.10.118-111.515.amzn2.x86_64.

A workaround would be:
auto requestStream = Aws::MakeShared<Aws::StringStream>(""); request.SetBody(requestStream);

Setting an empty stringstream as a body to the PutObjectRequest works around the segfault but is obviously not ideal.

[pcaswell]

I thought the correct solution would be to detect an empty body and set the MD5 NULL checksum value (which is d41d8cd98f00b204e9800998ecf8427e) base64 encoded in the header. The same approach could then be applied to the other checksum mechanisms. I tried it and S3 got a bad request response so I either did something wrong or AWS can't handle the NULL MD5 checksum.

[jmklix]

Thanks for the detailed writeup and finding a workaround. Looking into preventing the crash from happening

[jmklix]

Fix has been merged. Closing this issue

[github-actions]

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