From 40983356003f9412694953014ae9a4f2c2bfac7a Mon Sep 17 00:00:00 2001
From: Tim Schumacher <timschumi@gmx.de>
Date: Wed, 12 Apr 2023 16:03:36 +0200
Subject: [PATCH] LibCompress: Error on truncated uncompressed DEFLATE blocks

---
 Tests/LibCompress/TestGzip.cpp             | 12 ++++++++++++
 Userland/Libraries/LibCompress/Deflate.cpp |  3 +++
 2 files changed, 15 insertions(+)

diff --git a/Tests/LibCompress/TestGzip.cpp b/Tests/LibCompress/TestGzip.cpp
index 39082ca3572..be90cd88e83 100644
--- a/Tests/LibCompress/TestGzip.cpp
+++ b/Tests/LibCompress/TestGzip.cpp
@@ -95,3 +95,15 @@ TEST_CASE(gzip_round_trip)
     EXPECT(!uncompressed.is_error());
     EXPECT(uncompressed.value() == original);
 }
+
+TEST_CASE(gzip_truncated_uncompressed_block)
+{
+    Array<u8, 38> const compressed {
+        0x1F, 0x8B, 0x08, 0x13, 0x5D, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x85, 0x1C,
+        0x1C, 0xFF, 0xDB, 0xFB, 0xFF, 0xDB
+    };
+
+    auto const decompressed_or_error = Compress::GzipDecompressor::decompress_all(compressed);
+    EXPECT(decompressed_or_error.is_error());
+}
diff --git a/Userland/Libraries/LibCompress/Deflate.cpp b/Userland/Libraries/LibCompress/Deflate.cpp
index 92fa5884142..bdb7135f3e1 100644
--- a/Userland/Libraries/LibCompress/Deflate.cpp
+++ b/Userland/Libraries/LibCompress/Deflate.cpp
@@ -238,6 +238,9 @@ ErrorOr<bool> DeflateDecompressor::UncompressedBlock::try_read_more()
     if (m_bytes_remaining == 0)
         return false;
 
+    if (m_decompressor.m_input_stream->is_eof())
+        return Error::from_string_literal("Input data ends in the middle of an uncompressed DEFLATE block");
+
     Array<u8, 4096> temporary_buffer;
     auto readable_bytes = temporary_buffer.span().trim(min(m_bytes_remaining, m_decompressor.m_output_buffer.empty_space()));
     auto read_bytes = TRY(m_decompressor.m_input_stream->read_some(readable_bytes));