From 87c8b6395c5983fec12e19dfda0f4e83dead020c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rn=20Heusipp?= <manx@openmpt.org>
Date: Fri, 15 Mar 2024 11:44:11 +0000
Subject: [PATCH] Merged revision(s) 20335 from trunk/OpenMPT: [Fix]
 mpt/io_read/filedata_base_unseekable.hpp: Avoid memory denial-of-service when
 trying to read way more data than the actual file size from unseekable files.
 ........

git-svn-id: https://source.openmpt.org/svn/openmpt/branches/OpenMPT-1.31@20340 56274372-70c3-4bfc-bfc3-4c3a0b034d27
---
 src/mpt/io_read/filedata_base_unseekable.hpp | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/mpt/io_read/filedata_base_unseekable.hpp b/src/mpt/io_read/filedata_base_unseekable.hpp
index 874c32457b2..dbc8d4fe1e3 100644
--- a/src/mpt/io_read/filedata_base_unseekable.hpp
+++ b/src/mpt/io_read/filedata_base_unseekable.hpp
@@ -87,15 +87,14 @@ class FileDataUnseekable : public IFileData {
 			return;
 		}
 		std::size_t alignedpos = mpt::saturate_align_up<std::size_t>(target, QUANTUM_SIZE);
-		std::size_t needcount = alignedpos - cachesize;
-		EnsureCacheBuffer(needcount);
-		std::size_t readcount = InternalReadUnseekable(mpt::span(&cache[cachesize], alignedpos - cachesize)).size();
-		cachesize += readcount;
-		if (!InternalEof()) {
-			// can read further
-			return;
+		while (!InternalEof() && (cachesize < alignedpos)) {
+			EnsureCacheBuffer(BUFFER_SIZE);
+			std::size_t readcount = InternalReadUnseekable(mpt::span(&cache[cachesize], BUFFER_SIZE)).size();
+			cachesize += readcount;
+		}
+		if (InternalEof()) {
+			streamFullyCached = true;
 		}
-		streamFullyCached = true;
 	}
 
 private: