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Fix arbitrary dll load via json injection #2269

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Merged
kunal-vaishnavi merged 3 commits into from
Jul 13, 2026
Merged

Fix arbitrary dll load via json injection #2269

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33e5e9e
Fix arbitrary dll load via json injection
apsonawane Jul 6, 2026
be17e64
Address PR review: reject unsupported control chars in EscapeJsonString
apsonawane Jul 6, 2026
9ca7913
Merge branch 'main' into asonawane/load
apsonawane Jul 7, 2026
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40 changes: 38 additions & 2 deletions src/config.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#include "runtime_settings.h"
#include "json.h"
#include <algorithm>
#include <cstdio>
#include <fstream>
#include <sstream>
#include <limits>
Expand Down Expand Up @@ -1399,6 +1400,37 @@ void ClearProviders(Config& config) {
config.model.decoder.session_options.providers.clear();
}

// Escape a string for safe embedding inside a JSON string literal. Prevents JSON
// injection when caller-supplied values are concatenated into a JSON document that
// will subsequently be parsed (e.g. in SetProviderOption below). Handles the
// mandatory JSON escapes: quote, backslash, and the C0 control-character shortcuts.
// Any other control characters (< 0x20) are emitted as \u00XX.
static std::string EscapeJsonString(std::string_view s) {
std::string result;
result.reserve(s.size());
for (char c : s) {
switch (c) {
case '"': result += "\\\""; break;
case '\\': result += "\\\\"; break;
case '\b': result += "\\b"; break;
case '\f': result += "\\f"; break;
case '\n': result += "\\n"; break;
case '\r': result += "\\r"; break;
case '\t': result += "\\t"; break;
default:
if (static_cast<unsigned char>(c) < 0x20) {
char buf[7];
std::snprintf(buf, sizeof(buf), "\\u%04x", static_cast<unsigned char>(c));
result += buf;
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} else {
result += c;
}
break;
}
}
return result;
}

void SetProviderOption(Config& config, std::string_view provider_name, std::string_view option_name, std::string_view option_value) {
// Normalize the provider name once
auto normalized_provider = NormalizeProviderName(provider_name);
Expand All @@ -1421,10 +1453,14 @@ void SetProviderOption(Config& config, std::string_view provider_name, std::stri
}
}

// JSON-escape all caller-supplied string fragments before concatenating them into the
// JSON document. Without escaping, quote/backslash characters in provider_name,
// option_name, or option_value would let a caller inject arbitrary JSON structure
// (sibling keys, new provider entries, etc.) into the parsed configuration.
std::ostringstream json;
json << R"({")" << provider_name << R"(":{)";
json << R"({")" << EscapeJsonString(provider_name) << R"(":{)";
if (!option_name.empty()) {
json << R"(")" << option_name << R"(":")" << option_value << R"(")";
json << R"(")" << EscapeJsonString(option_name) << R"(":")" << EscapeJsonString(option_value) << R"(")";
}
json << R"(}})";

Expand Down
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