Stop the value command on the untrusted-safe allowlist crashing the daemon

glibc leaves endptr unset for a small invalid base; ERANGE throws instead of clamping.

src/command_ui.cc

@@ -2,6 +2,7 @@
 
 #include <sys/types.h>
 
+#include <cerrno>
 #include <ctime>
 #include <limits>
 #include <regex>
@@ -126,11 +127,20 @@ apply_value([[maybe_unused]] rpc::target_type target, const torrent::Object::lis
   if (args.front().is_value()) {
     val = args.front().as_value();
   } else {
-    int base = args.size() > 1 ? args.back().is_value() ?
-               args.back().as_value() : strtol(args.back().as_string().c_str(), NULL, 10) : 10;
+    int64_t base = args.size() > 1 ? args.back().is_value() ?
+                   args.back().as_value() : strtoll(args.back().as_string().c_str(), NULL, 10) : 10;
+
+    if (base != 0 && (base < 2 || base > 36))
+      throw torrent::input_error("'value' base must be 0 or between 2 and 36!");
+
     char* endptr = 0;
+    errno = 0;
 
     val = strtoll(args.front().as_string().c_str(), &endptr, base);
+
+    if (errno == ERANGE)
+      throw torrent::input_error("Number out of range: " + args.front().as_string());
+
     while (*endptr == ' ' || *endptr == '\n') ++endptr;
     if (*endptr)
       throw torrent::input_error("Junk at end of number: " + args.front().as_string());

test/src/test_command_dynamic.cc

@@ -2,6 +2,8 @@
 
 #include "test/src/test_command_dynamic.h"
 
+#include "helpers/assert.h"
+
 #include "control.h"
 #include "globals.h"
 #include "rpc/parse_commands.h"
@@ -82,3 +84,30 @@ TestCommandDynamic::test_insert_list() {
   CPPUNIT_ASSERT(filled.is_list());
   CPPUNIT_ASSERT_EQUAL((size_t)2, filled.as_list().size());
 }
+
+void
+TestCommandDynamic::test_value_base() {
+  auto value = [](std::initializer_list<torrent::Object> objects) {
+    auto args = torrent::Object::create_list();
+
+    for (const auto& object : objects)
+      args.as_list().push_back(object);
+
+    return rpc::commands.call_command("value", args).as_value();
+  };
+
+  CPPUNIT_ASSERT_EQUAL(int64_t(10), value({"10"}));
+  CPPUNIT_ASSERT_EQUAL(int64_t(255), value({"ff", int64_t(16)}));
+
+  // strtoll only defines base 0 and base 2 through 36.
+  ASSERT_CATCH_INPUT_ERROR( { value({"10", int64_t(1)}); } );
+  ASSERT_CATCH_INPUT_ERROR( { value({"10", int64_t(37)}); } );
+  ASSERT_CATCH_INPUT_ERROR( { value({"10", int64_t(-1)}); } );
+
+  // An out-of-range base must not be narrowed into a valid one.
+  ASSERT_CATCH_INPUT_ERROR( { value({"10", int64_t(1) << 40}); } );
+  ASSERT_CATCH_INPUT_ERROR( { value({"ff", (int64_t(1) << 32) + 16}); } );
+
+  // A number too large for the result must be rejected, not clamped.
+  ASSERT_CATCH_INPUT_ERROR( { value({"99999999999999999999999"}); } );
+}

test/src/test_command_dynamic.h

@@ -8,6 +8,7 @@ class TestCommandDynamic : public test_fixture {
   CPPUNIT_TEST(test_get_set);
   CPPUNIT_TEST(test_old_style);
   CPPUNIT_TEST(test_insert_list);
+  CPPUNIT_TEST(test_value_base);
 
   CPPUNIT_TEST_SUITE_END();
 
@@ -20,6 +21,7 @@ public:
 
   void test_old_style();
   void test_insert_list();
+  void test_value_base();
 
 private:
   std::unique_ptr<TestMainThread> m_test_main_thread;