diff --git a/Core/HLE/AtracCtx2.cpp b/Core/HLE/AtracCtx2.cpp
index 32f353971c..afa9ea9ef2 100644
--- a/Core/HLE/AtracCtx2.cpp
+++ b/Core/HLE/AtracCtx2.cpp
@@ -875,9 +875,13 @@ u32 Atrac2::DecodeInternal(u32 outbufAddr, int *SamplesNum, int *finish) {
 	int16_t *outPtr;
 
 	_dbg_assert_(samplesToDecode <= info.SamplesPerFrame());
-	if (samplesToDecode != info.SamplesPerFrame()) {
+	// info.codec is in guest memory and can be changed after SetData, so what the decoder actually
+	// writes is decided by the decoder.
+	const int decoderSamples = decoder_->GetAudioType() == PSP_CODEC_AT3PLUS ? ATRAC3PLUS_MAX_SAMPLES : ATRAC3_MAX_SAMPLES;
+	if (samplesToDecode != decoderSamples) {
 		if (!decodeTemp_) {
-			decodeTemp_ = new int16_t[info.SamplesPerFrame() * outputChannels_];
+			// Big enough for any frame, in any channel count.
+			decodeTemp_ = new int16_t[ATRAC3PLUS_MAX_SAMPLES * 2]();
 		}
 		outPtr = decodeTemp_;
 	} else {
@@ -887,8 +891,9 @@ u32 Atrac2::DecodeInternal(u32 outbufAddr, int *SamplesNum, int *finish) {
 	context_->codec.inBuf = inAddr;
 	context_->codec.outBuf = outbufAddr;
 
-	if (!Memory::IsValidAddress(inAddr)) {
-		ERROR_LOG(Log::Atrac, "DecodeInternal: Bad inAddr %08x", inAddr);
+	// The decoder reads a whole frame.
+	if (!Memory::IsValidRange(inAddr, info.sampleSize)) {
+		ERROR_LOG(Log::Atrac, "DecodeInternal: Bad inAddr %08x (frame size %d)", inAddr, info.sampleSize);
 		return SCE_ERROR_ATRAC_API_FAIL;
 	}
 
@@ -918,8 +923,8 @@ u32 Atrac2::DecodeInternal(u32 outbufAddr, int *SamplesNum, int *finish) {
 			*finish = 0;
 		}
 		u8 *outBuf = outbufAddr ? Memory::GetPointerWriteOrException(outbufAddr) : nullptr;
-		if (samplesToDecode != info.SamplesPerFrame() && samplesToDecode != 0 && outBuf) {
-			memcpy(outBuf, decodeTemp_, samplesToDecode * outputChannels_ * sizeof(int16_t));
+		if (outPtr == decodeTemp_ && samplesToDecode != 0 && outBuf) {
+			memcpy(outBuf, decodeTemp_, std::min(samplesToDecode, (int)ATRAC3PLUS_MAX_SAMPLES) * outputChannels_ * sizeof(int16_t));
 		}
 
 		// Handle increments and looping.
@@ -976,9 +981,11 @@ u32 Atrac2::DecodeInternal(u32 outbufAddr, int *SamplesNum, int *finish) {
 					size_t copyLen = info.secondBufferByte % info.sampleSize;
 					if (copyLen > info.bufferByte)
 						copyLen = info.bufferByte;
-					memcpy(Memory::GetPointerWriteOrException(info.buffer),
-						Memory::GetPointerOrException(info.secondBuffer + (info.secondBufferByte - info.secondBufferByte % info.sampleSize)),
-						copyLen);
+					const u32 copySrc = info.secondBuffer + (info.secondBufferByte - info.secondBufferByte % info.sampleSize);
+					// Both addresses come from the context in guest memory.
+					if (Memory::IsValidRange(info.buffer, (u32)copyLen) && Memory::IsValidRange(copySrc, (u32)copyLen)) {
+						memcpy(Memory::GetPointerWriteOrException(info.buffer), Memory::GetPointerOrException(copySrc), copyLen);
+					}
 				}
 			}
 		}
diff --git a/Core/HLE/sceAtrac.cpp b/Core/HLE/sceAtrac.cpp
index dd414c63a8..61b9dd26c4 100644
--- a/Core/HLE/sceAtrac.cpp
+++ b/Core/HLE/sceAtrac.cpp
@@ -420,7 +420,8 @@ static u32 sceAtracDecodeData(int atracID, u32 outAddr, u32 numSamplesAddr, u32
 	int numSamplesWritten = 0;
 	int finish = 0;
 	int remains = 0;
-	if (outAddr != 0 && !Memory::IsValidAddress(outAddr)) {
+	// A whole frame is written.
+	if (outAddr != 0 && !Memory::IsValidRange(outAddr, atrac->GetOutputChannels() * 2 * atrac->SamplesPerFrame())) {
 		// Dunno what error code to return here, but we have to bail in this case to avoid crashing PPSSPP.
 		return hleLogError(Log::Atrac, SCE_ERROR_ATRAC_SIZE_TOO_SMALL);
 	}
@@ -757,6 +758,13 @@ static u32 sceAtracResetPlayPosition(int atracID, int sample, int bytesWrittenFi
 	return hleDelayResult(res, "reset play pos", 3000);
 }
 
+
+// The track parsers read up to the size they're given, which the game picks. Bound it by what's
+// actually mapped, but keep it for invalid pointers so those are still reported as such.
+static u32 GuestReadableSize(u32 addr, u32 size) {
+	return Memory::IsValidAddress(addr) ? Memory::ClampValidSizeAt(addr, size) : size;
+}
+
 static u32 sceAtracSetHalfwayBuffer(int atracID, u32 buffer, u32 readSize, u32 bufferSize) {
 	AtracBase *atrac = getAtrac(atracID);
 	// Don't use AtracValidateManaged here.
@@ -770,7 +778,7 @@ static u32 sceAtracSetHalfwayBuffer(int atracID, u32 buffer, u32 readSize, u32 b
 
 	Track track;
 	std::string error;
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), readSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, readSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -807,7 +815,7 @@ static u32 sceAtracSetData(int atracID, u32 buffer, u32 bufferSize) {
 
 	Track track;
 	std::string error;
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), bufferSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, bufferSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -838,7 +846,7 @@ static int sceAtracSetDataAndGetID(u32 buffer, int bufferSize) {
 	std::string error;
 	// We let zero-pointer through as zeroes, so the small size check can kick in before it's accessed.
 	// This is needed in Tomb Raider Legend (#20145).
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), bufferSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, bufferSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -864,7 +872,7 @@ static int sceAtracSetHalfwayBufferAndGetID(u32 buffer, u32 readSize, u32 buffer
 
 	Track track;
 	std::string error;
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), readSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, readSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -990,7 +998,7 @@ static int sceAtracSetMOutHalfwayBuffer(int atracID, u32 buffer, u32 readSize, u
 
 	Track track;
 	std::string error;
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), readSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, readSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -1016,7 +1024,7 @@ static u32 sceAtracSetMOutData(int atracID, u32 buffer, u32 bufferSize) {
 
 	Track track;
 	std::string error;
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), bufferSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, bufferSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -1036,7 +1044,7 @@ static u32 sceAtracSetMOutData(int atracID, u32 buffer, u32 bufferSize) {
 static int sceAtracSetMOutDataAndGetID(u32 buffer, u32 bufferSize) {
 	Track track;
 	std::string error;
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), bufferSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, bufferSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -1065,7 +1073,7 @@ static int sceAtracSetMOutHalfwayBufferAndGetID(u32 buffer, u32 readSize, u32 bu
 
 	Track track;
 	std::string error;
-	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), readSize, &track, &error);
+	int ret = AnalyzeAtracTrack(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, readSize), &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -1090,7 +1098,7 @@ static int sceAtracSetMOutHalfwayBufferAndGetID(u32 buffer, u32 readSize, u32 bu
 static int sceAtracSetAA3DataAndGetID(u32 buffer, u32 bufferSize, u32 fileSize, u32 metadataSizeAddr) {
 	Track track;
 	std::string error;
-	int ret = AnalyzeAA3Track(Memory::GetPointerOrNull(buffer), bufferSize, fileSize, &track, &error);
+	int ret = AnalyzeAA3Track(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, bufferSize), fileSize, &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
@@ -1116,7 +1124,7 @@ static int sceAtracSetAA3HalfwayBufferAndGetID(u32 buffer, u32 readSize, u32 buf
 
 	Track track;
 	std::string error;
-	int ret = AnalyzeAA3Track(Memory::GetPointerOrNull(buffer), readSize, fileSize, &track, &error);
+	int ret = AnalyzeAA3Track(Memory::GetPointerOrNull(buffer), GuestReadableSize(buffer, readSize), fileSize, &track, &error);
 	if (ret < 0) {
 		return hleLogError(Log::Atrac, ret, "%s", error.c_str());
 	}
diff --git a/Core/HLE/sceAudiocodec.cpp b/Core/HLE/sceAudiocodec.cpp
index c8f346cc3c..5e5514ab7e 100644
--- a/Core/HLE/sceAudiocodec.cpp
+++ b/Core/HLE/sceAudiocodec.cpp
@@ -640,6 +640,12 @@ static int sceAudiocodecDecode(u32 ctxPtr, int codec) {
 		} else if (codec == PSP_CODEC_AT3PLUS && ctx->fmt.at3.outputChannels == 1) {
 			outputChannels = 1;
 		}
+		// The decoder writes a whole frame, but only the first byte of outBuf was checked.
+		const u32 maxFrameSamples = codec == PSP_CODEC_AT3PLUS ? 2048 : (codec == PSP_CODEC_MP3 ? 1152 : 1024);
+		if (!Memory::IsValidRange(ctx->outBuf, maxFrameSamples * outputChannels * 2)) {
+			ctx->err = 0x20b;
+			return hleLogError(Log::ME, 0, "Output buffer at %08x can't hold a frame", ctx->outBuf);
+		}
 		bool result = decoder->Decode(inBuf, bytesPerFrame, &inDataConsumed, outputChannels, outBuf, &outSamples);
 		if (!result && (codec == PSP_CODEC_AT3PLUS || codec == PSP_CODEC_AT3)) {
 			// What the hardware reports for a frame that doesn't decode (0x208 is also possible for
diff --git a/Core/HLE/sceMp3.cpp b/Core/HLE/sceMp3.cpp
index acd4e9edec..b180b0bd11 100644
--- a/Core/HLE/sceMp3.cpp
+++ b/Core/HLE/sceMp3.cpp
@@ -420,9 +420,10 @@ static int CalculateMp3SamplesPerFrame(int versionBits, int layerBits) {
 
 static int FindMp3Header(AuCtx *ctx, int &header, int end) {
 	u32 addr = ctx->AuBuf + ctx->AuStreamWorkareaSize();
-	if (Memory::IsValidRange(addr, end)) {
+	// A header is four bytes, read at each offset.
+	if (end >= 4 && Memory::IsValidRange(addr, end)) {
 		const u8 *ptr = Memory::GetPointerUnchecked(addr);
-		for (int offset = 0; offset < end; ++offset) {
+		for (int offset = 0; offset + 4 <= end; ++offset) {
 			// If we hit valid sync bits, then we've found a header.
 			if (ptr[offset] == 0xFF && (ptr[offset + 1] & 0xC0) == 0xC0) {
 				header = bswap32(Memory::ReadUnchecked_U32(addr + offset));
@@ -758,12 +759,17 @@ static u32 sceMp3LowLevelDecode(u32 mp3, u32 sourceAddr, u32 sourceBytesConsumed
 		return hleLogError(Log::ME, -1, "invalid address in args");
 	}
 
+	// A frame is at most 1152 stereo samples, and the decoder is handed up to 4096 bytes.
+	if (!Memory::IsValidRange(samplesAddr, 1152 * 2 * 2) || !Memory::IsValidRange(sourceBytesConsumedAddr, 4) || !Memory::IsValidRange(sampleBytesAddr, 4)) {
+		return hleLogError(Log::ME, -1, "invalid address in args");
+	}
 	const u8 *inbuff = Memory::GetPointerWriteUnchecked(sourceAddr);
 	int16_t *outbuf = (int16_t *)Memory::GetPointerWriteUnchecked(samplesAddr);
+	const int inBytes = (int)Memory::ClampValidSizeAt(sourceAddr, 4096);
 	
 	int outSamples = 0;
 	int inbytesConsumed = 0;
-	if (!ctx->decoder->Decode(inbuff, 4096, &inbytesConsumed, 2, outbuf, &outSamples)) {
+	if (!ctx->decoder->Decode(inbuff, inBytes, &inbytesConsumed, 2, outbuf, &outSamples)) {
 		WARN_LOG(Log::ME, "sceMp3LowLevelDecode: Decode failed");
 	}
 	int outBytes = outSamples * sizeof(int16_t) * 2;
diff --git a/Core/HLE/scePsmf.cpp b/Core/HLE/scePsmf.cpp
index f0c8070d27..d234f8ec41 100644
--- a/Core/HLE/scePsmf.cpp
+++ b/Core/HLE/scePsmf.cpp
@@ -295,9 +295,15 @@ public:
 		// the unwrapped count.
 		const u64 epMapBytes = EP_MAP_STRIDE * (u64)psmf->EPMapEntriesNum;
 		if (psmf->headerOffset != 0) {
-			if (epMapBytes > 0xFFFFFFFFull - psmf->EPMapOffset || !Memory::IsValidRange(psmf->headerOffset, psmf->EPMapOffset + (u32)epMapBytes)) {
+			// The entries are read from data + EPMapOffset, so the map has to start inside the
+			// address space (the sum used to wrap around to a valid address) and be mapped.
+			const u64 epMapAddr = (u64)psmf->headerOffset + psmf->EPMapOffset;
+			if (epMapAddr > 0xFFFFFFFFull || !Memory::IsValidAddress((u32)epMapAddr)) {
+				ERROR_LOG(Log::ME, "Invalid PSMF EP map offset: %08x", psmf->EPMapOffset);
+				psmf->EPMapEntriesNum = 0;
+			} else if (epMapBytes > 0xFFFFFFFFull - psmf->EPMapOffset || !Memory::IsValidRange(psmf->headerOffset, psmf->EPMapOffset + (u32)epMapBytes)) {
 				ERROR_LOG(Log::ME, "Invalid PSMF EP map entry count: %d", psmf->EPMapEntriesNum);
-				psmf->EPMapEntriesNum = Memory::ClampValidSizeAt(psmf->headerOffset + psmf->EPMapOffset, (u32)epMapBytes) / EP_MAP_STRIDE;
+				psmf->EPMapEntriesNum = Memory::ClampValidSizeAt((u32)epMapAddr, (u32)epMapBytes) / EP_MAP_STRIDE;
 			}
 		} else {
 			// No guest address to validate against (player tempbuf path,
@@ -770,7 +776,8 @@ static void DelayPsmfStateChange(u32 psmfPlayer, u32 newState, s64 delayUs) {
 }
 
 static u32 scePsmfSetPsmf(u32 psmfStruct, u32 psmfData) {
-	if (!Memory::IsValidAddress(psmfStruct) || !Memory::IsValidAddress(psmfData)) {
+	// The header fields Psmf reads go up to 0x82.
+	if (!Memory::IsValidAddress(psmfStruct) || !Memory::IsValidRange(psmfData, 0x82)) {
 		// Crashes on a PSP.
 		return hleReportError(Log::ME, SCE_KERNEL_ERROR_ILLEGAL_ADDRESS, "bad address");
 	}