{"record":{"id":"28a770216ea7ffaf","repo":"github/copilot-sdk","slug":"empty-pt-interp-segment","errorCode":null,"errorMessage":"Empty PT_INTERP segment","messagePattern":"Empty PT_INTERP segment","errorType":"exception","errorClass":"IOException","httpStatus":null,"severity":"error","filePath":"java/sdk/src/main/java/com/github/copilot/ffi/PlatformDetector.java","lineNumber":245,"sourceCode":"                pFileSize = readUInt32(probe, base + 16, littleEndian);\n            }\n\n            if (pOffset < 0 || pFileSize <= 0 || pOffset > Integer.MAX_VALUE || pFileSize > Integer.MAX_VALUE) {\n                throw new IOException(\"Invalid PT_INTERP bounds\");\n            }\n\n            int start = (int) pOffset;\n            int end = start + (int) pFileSize;\n            if (end > size) {\n                throw new IOException(\"PT_INTERP extends past probe window; increase probe size\");\n            }\n\n            int nulIndex = start;\n            while (nulIndex < end && probe[nulIndex] != 0) {\n                nulIndex++;\n            }\n            if (nulIndex == start) {\n                throw new IOException(\"Empty PT_INTERP segment\");\n            }\n            return new String(probe, start, nulIndex - start, StandardCharsets.UTF_8);\n        }\n\n        throw new IOException(\"ELF PT_INTERP segment not found\");\n    }\n\n    private static byte[] readPrefix(Path path, int maxBytes) throws IOException {\n        byte[] buffer = new byte[maxBytes];\n        int total = 0;\n        try (InputStream in = Files.newInputStream(path)) {\n            while (total < maxBytes) {\n                int read = in.read(buffer, total, maxBytes - total);\n                if (read < 0) {\n                    break;\n                }\n                total += read;\n            }","sourceCodeStart":227,"sourceCodeEnd":263,"githubUrl":"https://github.com/github/copilot-sdk/blob/cd8cf15dc3f9e762615790aaed0a771a0f392755/java/sdk/src/main/java/com/github/copilot/ffi/PlatformDetector.java#L227-L263","documentation":"A valid PT_INTERP segment contains a NUL-terminated interpreter path (e.g. /lib64/ld-linux-x86-64.so.2). If the first byte of the segment is already NUL, the path is empty, which cannot be a real interpreter, so an IOException is thrown instead of returning an empty string.","triggerScenarios":"A PT_INTERP entry whose p_filesz starts with a 0 byte at p_offset — a corrupt or adversarially crafted ELF, or misaligned decoding of program header fields from a bad probe.","commonSituations":"Corrupted binaries; fuzzed ELF inputs; header fields decoded with wrong endianness/class so p_offset points at padding instead of the .interp content.","solutions":["Validate the binary with `readelf -l <path>`; a real binary shows a non-empty interpreter — if so, fix your probe/decode logic (full read from offset 0, correct endianness).","Reinstall/re-download the binary and verify its checksum.","Reject corrupt/untrusted ELF inputs explicitly by catching IOException and reporting the file as invalid.","Check that p_offset/p_filesz were decoded after correctly determining ELF class and endianness."],"exampleFix":"// before\nString interp = readElfPtInterp(probe); // decodes p_offset with wrong endianness\n// after\nboolean littleEndian = (probe[5] & 0xFF) == 1; // EI_DATA before decoding\nlong pOffset = littleEndian ? readUInt32LE(probe, base + 8) : readUInt32BE(probe, base + 8);\nString interp = readElfPtInterp(probe);","handlingStrategy":"validation","validationCode":"// Reject obviously invalid ELF before parsing\nif (!isElf(probe) || probe.length < 64) throw new IOException(\"Invalid or corrupt ELF input\");","typeGuard":"static boolean isElf(byte[] probe) {\n    return probe != null && probe.length >= 4 && probe[0] == 0x7F\n        && probe[1] == 'E' && probe[2] == 'L' && probe[3] == 'F';\n}","tryCatchPattern":"try {\n    String interp = readElfPtInterp(probe);\n    if (interp.isEmpty()) throw new IOException(\"Empty PT_INTERP\");\n} catch (IOException e) {\n    throw new IOException(\"Corrupt ELF interpreter segment in \" + path + \": \" + e.getMessage(), e);\n}","preventionTips":["Decode p_offset/p_filesz only after confirming ELF class and endianness.","Validate binaries with `readelf -l <path>` and checksums before deployment.","Treat fuzzed/untrusted ELF inputs as expected rejections via try-catch.","Read probes from offset 0 of the real file to keep header offsets aligned."],"tags":["elf","binary-parsing","corruption","java"],"backgroundTag":"invalid-argument-format","analyzedSha":"cd8cf15dc3f9e762615790aaed0a771a0f392755","analyzedAt":"2026-09-09T18:32:31.973Z","contentChangedAt":"2026-09-09T18:32:31.973Z","schemaVersion":2},"datasetVersion":"2026-09-16T04:17:20.429Z"}