mirror of https://github.com/SixLabors/ImageSharp
Browse Source
* Fix integer overflow and bounds-checking vulnerabilities in EXR decoder Use ulong arithmetic in CalculateBytesPerRow and block size calculations to prevent integer overflow. Add validation for DataWindow dimensions, block size limits, and row offsets outside stream bounds. * Harden EXR row offset validation * EXR: validate sizes, prevent overflows, dispose image --------- Co-authored-by: James Jackson-South <james_south@hotmail.com>pull/3133/head
Sven Claesson
2 months ago
committed by
GitHub
GitHub
4 changed files with 384 additions and 35 deletions
@ -0,0 +1,274 @@ |
|||
// Copyright (c) Six Labors.
|
|||
// Licensed under the Six Labors Split License.
|
|||
|
|||
using System.Buffers.Binary; |
|||
using SixLabors.ImageSharp.Formats; |
|||
using SixLabors.ImageSharp.Formats.Exr; |
|||
using SixLabors.ImageSharp.PixelFormats; |
|||
|
|||
namespace SixLabors.ImageSharp.Tests.Formats.Exr; |
|||
|
|||
/// <summary>
|
|||
/// Security regression tests for the EXR decoder (Findings EXR-1, EXR-2, EXR-3).
|
|||
/// The EXR decoder was merged to main but not yet included in a tagged NuGet release.
|
|||
/// Each test demonstrates a crafted-input crash present in the unfixed code.
|
|||
/// </summary>
|
|||
[Trait("Format", "Exr")] |
|||
[ValidateDisposedMemoryAllocations] |
|||
public class ExrDecoderSecurityTests |
|||
{ |
|||
/// <summary>
|
|||
/// EXR-1 — EXR DataWindow Integer Overflow Produces Negative Image Dimensions (DoS)
|
|||
///
|
|||
/// Width and Height are computed from attacker-controlled DataWindow attributes
|
|||
/// using unchecked int subtraction:
|
|||
/// this.Width = XMax - XMin + 1 // overflows to -2147483647
|
|||
///
|
|||
/// The negative Width is then passed to the Image<TPixel> constructor, which calls
|
|||
/// Guard.MustBeGreaterThan(width, 0) → ArgumentOutOfRangeException.
|
|||
///
|
|||
/// After a fix this should throw InvalidImageContentException instead.
|
|||
///
|
|||
/// Affected file:
|
|||
/// src/ImageSharp/Formats/Exr/ExrDecoderCore.cs lines 600–601
|
|||
/// </summary>
|
|||
[Fact] |
|||
public void Decode_DataWindowOverflow_NegativeWidth_Throws() |
|||
{ |
|||
// XMin = -1073741825, XMax = 1073741823
|
|||
// Width = 1073741823 - (-1073741825) + 1 = 2^31 + 1 → wraps to -2147483647
|
|||
byte[] data = BuildMinimalExr(xMin: -1073741825, yMin: 0, xMax: 1073741823, yMax: 0); |
|||
|
|||
using var stream = new MemoryStream(data); |
|||
Assert.Throws<InvalidImageContentException>( |
|||
() => ExrDecoder.Instance.Decode<Rgba32>(DecoderOptions.Default, stream)); |
|||
} |
|||
|
|||
/// <summary>
|
|||
/// EXR-2 — EXR Row Offset Table Unvalidated Seek (DoS)
|
|||
///
|
|||
/// Row offsets are read from the file and used unconditionally to seek the stream:
|
|||
/// ulong rowOffset = this.ReadUnsignedLong(stream);
|
|||
/// stream.Position = (long)rowOffset; // no bounds check
|
|||
///
|
|||
/// A crafted offset of 0xFFFFFFFFFFFFFFFF casts to −1 as long, causing
|
|||
/// an ArgumentOutOfRangeException when setting stream.Position.
|
|||
///
|
|||
/// After a fix this should throw InvalidImageContentException instead.
|
|||
///
|
|||
/// Affected file:
|
|||
/// src/ImageSharp/Formats/Exr/ExrDecoderCore.cs lines 170–175 (scanline)
|
|||
/// lines 243–248 (tile)
|
|||
/// </summary>
|
|||
[Fact] |
|||
public void Decode_CraftedRowOffsets_OutOfBounds_Throws() |
|||
{ |
|||
// Valid 2×2 image (XMin=0,YMin=0,XMax=1,YMax=1 → Width=2,Height=2).
|
|||
// Row offset table immediately follows the header null byte:
|
|||
// 2 rows × 8 bytes each, all set to 0xFFFFFFFFFFFFFFFF.
|
|||
byte[] invalidOffsets = new byte[16]; |
|||
BinaryPrimitives.WriteUInt64LittleEndian(invalidOffsets, 0xFFFFFFFFFFFFFFFF); |
|||
BinaryPrimitives.WriteUInt64LittleEndian(invalidOffsets.AsSpan(8), 0xFFFFFFFFFFFFFFFF); |
|||
|
|||
byte[] data = BuildMinimalExr( |
|||
xMin: 0, yMin: 0, xMax: 1, yMax: 1, |
|||
rowOffsetTableAppend: invalidOffsets); |
|||
|
|||
using var stream = new MemoryStream(data); |
|||
Assert.Throws<InvalidImageContentException>( |
|||
() => ExrDecoder.Instance.Decode<Rgba32>(DecoderOptions.Default, stream)); |
|||
} |
|||
|
|||
[Fact] |
|||
public void Decode_CraftedRowOffsets_IntoHeader_Throws() |
|||
{ |
|||
// Offset 0 points back into the EXR file header and must be rejected
|
|||
// before the decoder seeks to attacker-controlled non-pixel data.
|
|||
byte[] headerOffsets = new byte[16]; |
|||
|
|||
byte[] data = BuildMinimalExr( |
|||
xMin: 0, yMin: 0, xMax: 1, yMax: 1, |
|||
rowOffsetTableAppend: headerOffsets); |
|||
|
|||
using var stream = new MemoryStream(data); |
|||
Assert.Throws<InvalidImageContentException>( |
|||
() => ExrDecoder.Instance.Decode<Rgba32>(DecoderOptions.Default, stream)); |
|||
} |
|||
|
|||
[Fact] |
|||
public void Decode_CraftedRowOffsets_IntoOffsetTable_Throws() |
|||
{ |
|||
byte[] data = BuildMinimalExr( |
|||
xMin: 0, yMin: 0, xMax: 1, yMax: 1, |
|||
rowOffsetTableAppend: new byte[16]); |
|||
|
|||
// Point the first row offset at the second row offset entry.
|
|||
BinaryPrimitives.WriteUInt64LittleEndian(data.AsSpan(data.Length - 16), (ulong)(data.Length - 8)); |
|||
|
|||
using var stream = new MemoryStream(data); |
|||
Assert.Throws<InvalidImageContentException>( |
|||
() => ExrDecoder.Instance.Decode<Rgba32>(DecoderOptions.Default, stream)); |
|||
} |
|||
|
|||
/// <summary>
|
|||
/// EXR-3 — Oversized EXR RGBA row sizing is rejected as invalid image content.
|
|||
///
|
|||
/// With 4 RGBA HALF channels and Width = 2^29, the decoded row staging and
|
|||
/// bytes-per-row arithmetic both exceed the supported buffer sizing limits.
|
|||
/// The decoder must reject this as InvalidImageContentException before any allocation.
|
|||
///
|
|||
/// Affected file:
|
|||
/// src/ImageSharp/Formats/Exr/ExrDecoderCore.cs lines 142–150, 215–223
|
|||
/// src/ImageSharp/Formats/Exr/ExrUtils.cs CalculateBytesPerRow
|
|||
/// </summary>
|
|||
[Fact] |
|||
public void Decode_RgbaRowSizingExceedsBufferLimits_Throws() |
|||
{ |
|||
// 4 RGBA HALF channels at this width cannot be represented by the decoder's
|
|||
// int-sized row staging or block buffers.
|
|||
byte[] data = BuildMinimalRgbaExr(xMin: 0, yMin: 0, xMax: 536870911, yMax: 0); |
|||
|
|||
using var stream = new MemoryStream(data); |
|||
Assert.Throws<InvalidImageContentException>( |
|||
() => ExrDecoder.Instance.Decode<Rgba32>(DecoderOptions.Default, stream)); |
|||
} |
|||
|
|||
[Fact] |
|||
public void Decode_DataWindowWidthExceedsRowBufferLimit_Throws() |
|||
{ |
|||
// A single HALF channel keeps bytesPerBlock below int.MaxValue, but the decoder
|
|||
// still stages four color planes and must reject widths that overflow width × 4.
|
|||
byte[] data = BuildMinimalExr(xMin: 0, yMin: 0, xMax: int.MaxValue / 4, yMax: 0); |
|||
|
|||
using var stream = new MemoryStream(data); |
|||
Assert.Throws<InvalidImageContentException>( |
|||
() => ExrDecoder.Instance.Decode<Rgba32>(DecoderOptions.Default, stream)); |
|||
} |
|||
|
|||
[Fact] |
|||
public void Identify_RowOffsetTableExceedsStream_Throws() |
|||
{ |
|||
// Identify parses the header only, so this verifies the offset table bound is
|
|||
// validated before scanline decoding reads from the table.
|
|||
byte[] data = BuildMinimalExr(xMin: 0, yMin: 0, xMax: 1, yMax: 1); |
|||
|
|||
using var stream = new MemoryStream(data); |
|||
Assert.Throws<InvalidImageContentException>( |
|||
() => ExrDecoder.Instance.Identify(DecoderOptions.Default, stream)); |
|||
} |
|||
|
|||
// -------------------------------------------------------------------------
|
|||
// Helpers: construct minimal valid-enough EXR scanline files.
|
|||
//
|
|||
// Required attributes per ParseHeaderAttributes validation:
|
|||
// channels, compression, dataWindow, displayWindow,
|
|||
// lineOrder, pixelAspectRatio, screenWindowCenter, screenWindowWidth
|
|||
// -------------------------------------------------------------------------
|
|||
|
|||
private static byte[] BuildMinimalExr( |
|||
int xMin, int yMin, int xMax, int yMax, |
|||
byte[] rowOffsetTableAppend = null) |
|||
{ |
|||
// channels: single "R" HALF channel with xSampling=1, ySampling=1
|
|||
// Layout per ReadChannelInfo: name\0 (2) + pixelType (4) + pLinear+reserved (4)
|
|||
// + xSampling (4) + ySampling (4) = 18 bytes/channel
|
|||
// + list-null (1) = 19 total
|
|||
byte[] channelData = |
|||
[ |
|||
0x52, 0x00, // "R\0"
|
|||
0x01, 0x00, 0x00, 0x00, // pixelType = Half (1)
|
|||
0x00, 0x00, 0x00, 0x00, // pLinear + 3 reserved bytes
|
|||
0x01, 0x00, 0x00, 0x00, // xSampling = 1
|
|||
0x01, 0x00, 0x00, 0x00, // ySampling = 1
|
|||
0x00, // channel-list null terminator
|
|||
]; |
|||
|
|||
return BuildExrWithChannels(xMin, yMin, xMax, yMax, channelData, rowOffsetTableAppend); |
|||
} |
|||
|
|||
private static byte[] BuildMinimalRgbaExr(int xMin, int yMin, int xMax, int yMax) |
|||
{ |
|||
// 4 HALF channels in alphabetical order (A, B, G, R) per EXR spec.
|
|||
// 18 bytes per channel × 4 channels + 1 list-null = 73 bytes total.
|
|||
byte[] channelData = |
|||
[ |
|||
0x41, 0x00, // "A\0"
|
|||
0x01, 0x00, 0x00, 0x00, // pixelType = Half (1)
|
|||
0x00, 0x00, 0x00, 0x00, // pLinear + 3 reserved bytes
|
|||
0x01, 0x00, 0x00, 0x00, // xSampling = 1
|
|||
0x01, 0x00, 0x00, 0x00, // ySampling = 1
|
|||
0x42, 0x00, // "B\0"
|
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x00, 0x00, 0x00, 0x00, |
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x47, 0x00, // "G\0"
|
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x00, 0x00, 0x00, 0x00, |
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x52, 0x00, // "R\0"
|
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x00, 0x00, 0x00, 0x00, |
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x01, 0x00, 0x00, 0x00, |
|||
0x00, // channel-list null terminator
|
|||
]; |
|||
|
|||
return BuildExrWithChannels(xMin, yMin, xMax, yMax, channelData); |
|||
} |
|||
|
|||
private static byte[] BuildExrWithChannels( |
|||
int xMin, int yMin, int xMax, int yMax, |
|||
byte[] channelData, |
|||
byte[] rowOffsetTableAppend = null) |
|||
{ |
|||
using var ms = new MemoryStream(); |
|||
using var bw = new BinaryWriter(ms, System.Text.Encoding.ASCII, leaveOpen: true); |
|||
|
|||
// Magic (0x01312F76 LE) + version 2, scanline (flags = 0x00)
|
|||
bw.Write(new byte[] { 0x76, 0x2F, 0x31, 0x01, 0x02, 0x00, 0x00, 0x00 }); |
|||
|
|||
void WriteAttr(string name, string type, byte[] payload) |
|||
{ |
|||
foreach (char c in name) bw.Write((byte)c); |
|||
bw.Write((byte)0); |
|||
foreach (char c in type) bw.Write((byte)c); |
|||
bw.Write((byte)0); |
|||
bw.Write(payload.Length); |
|||
bw.Write(payload); |
|||
} |
|||
|
|||
WriteAttr("channels", "chlist", channelData); |
|||
|
|||
WriteAttr("compression", "compression", [0x00]); // None
|
|||
|
|||
byte[] dw = new byte[16]; |
|||
BinaryPrimitives.WriteInt32LittleEndian(dw, xMin); |
|||
BinaryPrimitives.WriteInt32LittleEndian(dw.AsSpan(4), yMin); |
|||
BinaryPrimitives.WriteInt32LittleEndian(dw.AsSpan(8), xMax); |
|||
BinaryPrimitives.WriteInt32LittleEndian(dw.AsSpan(12), yMax); |
|||
WriteAttr("dataWindow", "box2i", dw); |
|||
|
|||
WriteAttr("displayWindow", "box2i", new byte[16]); // all zeros (0,0,0,0)
|
|||
|
|||
WriteAttr("lineOrder", "lineOrder", [0x00]); // IncreasingY
|
|||
|
|||
byte[] aspect = new byte[4]; |
|||
BinaryPrimitives.WriteSingleLittleEndian(aspect, 1.0f); |
|||
WriteAttr("pixelAspectRatio", "float", aspect); |
|||
|
|||
WriteAttr("screenWindowCenter", "v2f", new byte[8]); // (0f, 0f)
|
|||
|
|||
byte[] sww = new byte[4]; |
|||
BinaryPrimitives.WriteSingleLittleEndian(sww, 1.0f); |
|||
WriteAttr("screenWindowWidth", "float", sww); |
|||
|
|||
bw.Write((byte)0x00); // end-of-header sentinel
|
|||
|
|||
if (rowOffsetTableAppend is not null) |
|||
bw.Write(rowOffsetTableAppend); |
|||
|
|||
return ms.ToArray(); |
|||
} |
|||
} |
|||
Loading…
Reference in new issue