Fixed check for buffer overflow.

brianberns · brianberns · commit f78f2344142b · 2025-09-16T23:48:08.000-04:00
diff --git a/src/ImageSharp/Formats/Tiff/Compression/Decompressors/LzwString.cs b/src/ImageSharp/Formats/Tiff/Compression/Decompressors/LzwString.cs
@@ -77,9 +77,9 @@ public int WriteTo(Span<byte> buffer, int offset)
 
         LzwString e = this;
         int endIdx = this.Length - 1;
-        if (endIdx >= buffer.Length)
+        if (offset + endIdx >= buffer.Length)
         {
-            TiffThrowHelper.ThrowImageFormatException("Error reading lzw compressed stream. Either pixel buffer to write to is to small or code length is invalid!");
+            TiffThrowHelper.ThrowImageFormatException("Error reading lzw compressed stream. Either pixel buffer to write to is too small or code length is invalid!");
         }
 
         for (int i = endIdx; i >= 0; i--)

Original file line number	Diff line number	Diff line change
`@@ -77,9 +77,9 @@ public int WriteTo(Span<byte> buffer, int offset)`
`77`	`77`
`78`	`78`	`LzwString e = this;`
`79`	`79`	`int endIdx = this.Length - 1;`
`80`		`- if (endIdx >= buffer.Length)`
	`80`	`+ if (offset + endIdx >= buffer.Length)`
`81`	`81`	`{`
`82`		`- TiffThrowHelper.ThrowImageFormatException("Error reading lzw compressed stream. Either pixel buffer to write to is to small or code length is invalid!");`
	`82`	`+ TiffThrowHelper.ThrowImageFormatException("Error reading lzw compressed stream. Either pixel buffer to write to is too small or code length is invalid!");`
`83`	`83`	`}`
`84`	`84`
`85`	`85`	`for (int i = endIdx; i >= 0; i--)`