fix(audio): add additional biquad filter validation checks

- Add state pointer null checks in Process() and Verify()
- Add sample count validation
- Add buffer bounds checking with proper offset calculations
- Handle negative output indices with in-place processing fallback
- Improve error logging for debugging

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/audio_core/renderer/effect/biquad_filter.cpp

@@ -1,6 +1,8 @@
 // SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <algorithm>
+
 #include "audio_core/renderer/effect/biquad_filter.h"
 
 namespace AudioCore::Renderer {
@@ -11,9 +13,45 @@ void BiquadFilterInfo::Update(BehaviorInfo::ErrorInfo& error_info,
     auto params{reinterpret_cast<ParameterVersion1*>(parameter.data())};
 
     std::memcpy(params, in_specific, sizeof(ParameterVersion1));
+
+    // Check for corrupted parameters - if detected, disable the effect to prevent audio issues
+    bool parameters_valid = true;
+
+    // Validate channel_count
+    if (params->channel_count < 0 || params->channel_count > MaxChannels) {
+        LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid channel_count {}, disabling effect",
+                    params->channel_count);
+        parameters_valid = false;
+    }
+
+    // Validate parameter state
+    if (static_cast<u8>(params->state) > static_cast<u8>(EffectInfoBase::ParameterState::Updated)) {
+        LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid parameter state {}, disabling effect",
+                    static_cast<u8>(params->state));
+        parameters_valid = false;
+    }
+
+    // Validate input/output buffer indices
+    for (s8 i = 0; i < MaxChannels && parameters_valid; i++) {
+        // Negative values are allowed (indicate unused channels), but check for out-of-range values
+        if (params->inputs[i] < -1 || params->inputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid input buffer index {} for channel {}, disabling effect",
+                        params->inputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+        if (params->outputs[i] < -1 || params->outputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid output buffer index {} for channel {}, disabling effect",
+                        params->outputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+    }
+
     mix_id = in_params.mix_id;
     process_order = in_params.process_order;
-    enabled = in_params.enabled;
+    // Disable effect if parameters are corrupted to prevent audio issues
+    enabled = in_params.enabled && parameters_valid;
 
     error_info.error_code = ResultSuccess;
     error_info.address = CpuAddr(0);
@@ -25,9 +63,40 @@ void BiquadFilterInfo::Update(BehaviorInfo::ErrorInfo& error_info,
     auto params{reinterpret_cast<ParameterVersion2*>(parameter.data())};
 
     std::memcpy(params, in_specific, sizeof(ParameterVersion2));
+
+    // Validate parameters - ParameterVersion2 uses native float coefficients and has an enable field
+    bool parameters_valid = true;
+
+    // Validate channel_count using the standard validation function
+    if (!IsChannelCountValid(static_cast<u16>(params->channel_count))) {
+        LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid channel_count {}, disabling effect",
+                    params->channel_count);
+        parameters_valid = false;
+    }
+
+    // Validate input/output buffer indices only for active channels
+    const s8 active_channels = parameters_valid ? params->channel_count : 0;
+    for (s8 i = 0; i < active_channels && parameters_valid; i++) {
+        // Negative values are allowed (indicate unused channels), but check for out-of-range values
+        if (params->inputs[i] < -1 || params->inputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid input buffer index {} for channel {}, disabling effect",
+                        params->inputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+        if (params->outputs[i] < -1 || params->outputs[i] >= static_cast<s8>(MaxChannels * 2)) {
+            LOG_WARNING(Service_Audio, "BiquadFilterInfo: Invalid output buffer index {} for channel {}, disabling effect",
+                        params->outputs[i], i);
+            parameters_valid = false;
+            break;
+        }
+    }
+
     mix_id = in_params.mix_id;
     process_order = in_params.process_order;
-    enabled = in_params.enabled;
+    // ParameterVersion2 has its own enable field at the parameter level
+    // Combine with in_params.enabled and parameter validation
+    enabled = in_params.enabled && parameters_valid && params->enable;
 
     error_info.error_code = ResultSuccess;
     error_info.address = CpuAddr(0);