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[Mono] Fix ParameterInfo.Name to return null for unnamed parameters #121105

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[Mono] Fix ParameterInfo.Name to return null for unnamed parameters #121105

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66625bc
[Mono] Fix ParameterInfo.Name to return null for unnamed parameters
medhatiwari Oct 27, 2025
82d2738
correct unsafe callers
medhatiwari Oct 27, 2025
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2 changes: 1 addition & 1 deletion src/mono/mono/component/debugger-agent.c
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Expand Up @@ -9324,7 +9324,7 @@ method_commands_internal (int command, MonoMethod *method, MonoDomain *domain, g
names = g_new (char *, sig->param_count);
mono_method_get_param_names_internal (method, (const char **) names);
for (guint16 i = 0; i < sig->param_count; ++i)
buffer_add_string (buf, names [i]);
buffer_add_string (buf, names [i] ? names [i] : "");
g_free (names);

break;
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2 changes: 1 addition & 1 deletion src/mono/mono/metadata/loader.c
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Expand Up @@ -1446,7 +1446,7 @@ mono_method_get_param_names_internal (MonoMethod *method, const char **names)
return;

for (i = 0; i < signature->param_count; ++i)
names [i] = "";
names [i] = NULL;
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mono_method_get_param_names_internal is called by a couple of other methods. We need to make sure that each of them expects and handles NULL value. This seems to produce quite a few crashes on CI, primarily around aot compilation, but it looks like debugger could also suffer.

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@BrzVlad Thank you for catching this! I've audited all callers of mono_method_get_param_names_internal and found 2 unsafe callers
debugger-agent.c:9327 - Added NULL check: names[i] ? names[i] : ""
dwarfwriter.c:1868 - Added NULL check: !pname || pname[0] == '\0'

and other callers (mini-llvm.c (lines 4168, 13298) - checks if (names[i]), debug-mini.c:680 - uses ternary names[i] ? names[i] : "unknown name"

already loosk safe
Please let me know if I'm missing something here or if there are other callers I should check.


klass = method->klass;
if (m_class_get_rank (klass))
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9 changes: 7 additions & 2 deletions src/mono/mono/metadata/reflection.c
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Expand Up @@ -1017,8 +1017,13 @@ add_parameter_object_to_array (MonoMethod *method, MonoObjectHandle member, int
goto_if_nok (error, leave);

MonoStringHandle name_str;
name_str = mono_string_new_handle (name, error);
goto_if_nok (error, leave);
if (name != NULL) {
name_str = mono_string_new_handle (name, error);
goto_if_nok (error, leave);
} else {
// Keep NULL as NULL instead of converting to empty string
name_str = MONO_HANDLE_NEW (MonoString, NULL);
}

MonoObjectHandle def_value;

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2 changes: 1 addition & 1 deletion src/mono/mono/mini/dwarfwriter.c
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Expand Up @@ -1865,7 +1865,7 @@ mono_dwarf_writer_emit_method (MonoDwarfWriter *w, MonoCompile *cfg, MonoMethod

emit_uleb128 (w, need_loclist ? ABBREV_PARAM_LOCLIST : ABBREV_PARAM);
/* name */
if (pname[0] == '\0') {
if (!pname || pname[0] == '\0') {
sprintf (pname_buf, "param%d", i - sig->hasthis);
pname = pname_buf;
}
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