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Security: Unbounded memory consumption when buffering S3 object streams #312

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Security: Unbounded memory consumption when buffering S3 object streams #312

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37 changes: 35 additions & 2 deletions lib/s3-service.js
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,31 @@
// Require AWS SDK
const { S3Client, GetObjectCommand } = require('@aws-sdk/client-s3'); // AWS SDK
const { getSignedUrl } = require('@aws-sdk/s3-request-presigner');
const { streamToBuffer } = require('./utils');
const MAX_BUFFERED_OBJECT_SIZE = parseInt(
process.env.AWS_S3_MAX_BUFFERED_OBJECT_SIZE ||
process.env.AWS_S3_MAX_OBJECT_SIZE ||
10485760,
10
);

const streamToBufferWithLimit = async (stream, maxSize) => {
const chunks = [];
let size = 0;

for await (const chunk of stream) {
const buffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk);
size += buffer.length;

if (size > maxSize) {
if (typeof stream.destroy === 'function') stream.destroy();
throw new Error('S3 object exceeds maximum allowed buffered size');
}

chunks.push(buffer);
}

return Buffer.concat(chunks);
};

// Export
exports.client = new S3Client();
Expand All @@ -21,9 +45,18 @@ exports.getObject = (params) => {

if (!res.Body) return res;

if (
Number.isFinite(MAX_BUFFERED_OBJECT_SIZE) &&
MAX_BUFFERED_OBJECT_SIZE > 0 &&
typeof res.ContentLength === 'number' &&
res.ContentLength > MAX_BUFFERED_OBJECT_SIZE
) {
throw new Error('S3 object exceeds maximum allowed buffered size');
}

return {
...res,
Body: await streamToBuffer(res.Body),
Body: await streamToBufferWithLimit(res.Body, MAX_BUFFERED_OBJECT_SIZE),
};
},
};
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