Size CCITT encoder output buffers

src/ImageSharp/Formats/Tiff/Compression/Compressors/T4BitCompressor.cs

@@ -126,6 +126,14 @@ internal sealed class T4BitCompressor : TiffCcittCompressor
         }
     }
 
+    /// <inheritdoc />
+    protected override long GetMaximumEncodedBits(int rowsPerStrip)
+    {
+        // A pixel can require a 13-bit terminating code. Each row can also require
+        // an 8-bit zero-length white run and a 12-bit EOL, plus the initial EOL.
+        return 12L + ((((long)this.Width * 13) + 20) * rowsPerStrip);
+    }
+
     private void WriteEndOfLine(Span<byte> compressedData)
     {
         if (this.useModifiedHuffman)

src/ImageSharp/Formats/Tiff/Compression/Compressors/T6BitCompressor.cs

@@ -131,6 +131,14 @@ internal sealed class T6BitCompressor : TiffCcittCompressor
         this.WriteCode(12, 1, compressedData);
     }
 
+    /// <inheritdoc />
+    protected override long GetMaximumEncodedBits(int rowsPerStrip)
+    {
+        // Alternating pixels use at most 29 bits per two-pixel horizontal mode.
+        // Allow 16 bits per pixel, row transition overhead, and the final 24-bit EOFB.
+        return ((((long)this.Width * 16) + 24) * rowsPerStrip) + 24;
+    }
+
     /// <inheritdoc />
     protected override void Dispose(bool disposing)
     {

src/ImageSharp/Formats/Tiff/Compression/Compressors/TiffCcittCompressor.cs

@@ -465,6 +465,12 @@ internal abstract class TiffCcittCompressor : TiffBaseCompressor
     /// <param name="compressedData">The destination buffer to write the code to.</param>
     protected void WriteCode(uint codeLength, uint code, Span<byte> compressedData)
     {
+        long availableBits = (((long)compressedData.Length - this.bytePosition) * 8) - this.bitPosition;
+        if (codeLength > availableBits)
+        {
+            throw new InvalidMemoryOperationException("The CCITT output buffer is too small for the encoded data.");
+        }
+
         while (codeLength > 0)
         {
             int bitNumber = (int)codeLength;
@@ -526,8 +532,20 @@ internal abstract class TiffCcittCompressor : TiffBaseCompressor
     /// <inheritdoc/>
     public override void Initialize(int rowsPerStrip)
     {
-        // This is too much memory allocated, but just 1 bit per pixel will not do, if the compression rate is not good.
+        long maxNeededBits = this.GetMaximumEncodedBits(rowsPerStrip);
-        int maxNeededBytes = this.Width * rowsPerStrip;
+        ulong maxNeededBytes = (ulong)((maxNeededBits + 7) / 8);
-        this.compressedDataBuffer = this.Allocator.Allocate<byte>(maxNeededBytes);
+        if (maxNeededBytes > int.MaxValue)
+        {
+            InvalidMemoryOperationException.ThrowAllocationOverLimitException(maxNeededBytes, int.MaxValue);
+        }
+
+        this.compressedDataBuffer = this.Allocator.Allocate<byte>((int)maxNeededBytes);
     }
+
+    /// <summary>
+    /// Gets an upper bound for the encoded strip length in bits.
+    /// </summary>
+    /// <param name="rowsPerStrip">The number of rows in the strip.</param>
+    /// <returns>The maximum encoded length.</returns>
+    protected abstract long GetMaximumEncodedBits(int rowsPerStrip);
 }

tests/ImageSharp.Tests/Formats/Tiff/TiffEncoderTests.cs

@@ -554,6 +554,27 @@ public class TiffEncoderTests : TiffEncoderBaseTester
     public void TiffEncoder_EncodeBiColor_WithCcittGroup3FaxCompression_BlackIsZero_Works<TPixel>(TestImageProvider<TPixel> provider)
         where TPixel : unmanaged, IPixel<TPixel> => TestTiffEncoderCore(provider, TiffBitsPerPixel.Bit1, TiffPhotometricInterpretation.BlackIsZero, TiffCompression.CcittGroup3Fax);
 
+    [Fact]
+    public void TiffEncoder_EncodeNarrowCcittGroup3Fax_Works()
+    {
+        using Image<L8> image = new(1, 2000);
+        for (int y = 0; y < image.Height; y++)
+        {
+            image[0, y] = new L8((byte)((y & 1) == 0 ? 255 : 0));
+        }
+
+        TiffFrameMetadata metadata = image.Frames.RootFrame.Metadata.GetTiffMetadata();
+        metadata.BitsPerPixel = TiffBitsPerPixel.Bit1;
+        metadata.Compression = TiffCompression.CcittGroup3Fax;
+
+        using MemoryStream output = new();
+        image.Save(output, new TiffEncoder());
+
+        output.Position = 0;
+        using Image<L8> decoded = Image.Load<L8>(output);
+        Assert.Equal(image.Size, decoded.Size);
+    }
+
     [Theory]
     [WithFile(Issues2255, PixelTypes.Rgba32)]
     public void TiffEncoder_EncodeBiColor_WithCcittGroup3FaxCompression_WithoutSpecifyingBitPerPixel_Works<TPixel>(TestImageProvider<TPixel> provider)