Skip to content

[3.1] Backport #3075 - Add check, if Offset is greater then stream length when reading bitmap colorMapSize #3091

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
antonfirsov wants to merge 2 commits into
base: release/3.1.x
Choose a base branch
from
+34 −0
Open

[3.1] Backport #3075 - Add check, if Offset is greater then stream length when reading bitmap colorMapSize #3091

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
d3b1cb2
backport #3075 to 3.1
antonfirsov Mar 17, 2026
e114f00
Merge branch 'release/3.1.x' into af/backport-3075-to-3.1
JimBobSquarePants Mar 18, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1445,6 +1445,12 @@ private int ReadImageHeaders(BufferedReadStream stream, out bool inverted, out b
switch (this.fileMarkerType)
{
case BmpFileMarkerType.Bitmap:
if (this.fileHeader.Offset > stream.Length)
{
BmpThrowHelper.ThrowInvalidImageContentException(
$"Pixel data offset {this.fileHeader.Offset} exceeds file size {stream.Length}.");
}

colorMapSizeBytes = this.fileHeader.Offset - BmpFileHeader.Size - this.infoHeader.HeaderSize;
int colorCountForBitDepth = ColorNumerics.GetColorCountForBitDepth(this.infoHeader.BitsPerPixel);
bytesPerColorMapEntry = colorMapSizeBytes / colorCountForBitDepth;
Expand Down
28 changes: 28 additions & 0 deletions tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -571,6 +571,34 @@ public void BmpDecoder_ThrowsException_Issue2696<TPixel>(TestImageProvider<TPixe
Assert.IsType<InvalidMemoryOperationException>(ex.InnerException);
}

// https://github.com/SixLabors/ImageSharp/issues/3074
[Fact]
public void BmpDecoder_ThrowsException_Issue3074()
{
// Crafted BMP: pixel data offset = 0x7FFFFFFF, actual file = 35 bytes
byte[] data =
[
0x42, 0x4D, // "BM" signature
0x3A, 0x00, 0x00, 0x00, // file size: 58
0x00, 0x00, 0x00, 0x00, // reserved
0xFF, 0xFF, 0xFF, 0x7F, // pixel offset: 0x7FFFFFFF (2,147,483,647)
0x28, 0x00, 0x00, 0x00, // DIB header size: 40
0x01, 0x00, 0x00, 0x00, // width: 1
0x01, 0xFF, 0x00, 0x00, // height: 65281
0x01, 0x00, // color planes: 1
0x08, 0x00, // bits per pixel: 8
0x00, 0x00, 0x00, 0x00, // compression: RGB
0x00, 0x00, 0x00 // (truncated)
];

using MemoryStream stream = new(data);

Assert.Throws<InvalidImageContentException>(() =>
{
using Image<Rgba32> image = Image.Load<Rgba32>(stream);
});
}

[Fact]
public void BmpDecoder_ThrowsException_Issue3067()
{
Expand Down
Loading