From c114ca02dd09421e940dbdde98b1ca0b558bdd71 Mon Sep 17 00:00:00 2001
From: Ryan Oldenburg <guzba8@gmail.com>
Date: Fri, 20 Nov 2020 13:51:43 -0600
Subject: [PATCH] data len check

---
 src/pixie/fileformats/bmp.nim | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/pixie/fileformats/bmp.nim b/src/pixie/fileformats/bmp.nim
index f532654..d555960 100644
--- a/src/pixie/fileformats/bmp.nim
+++ b/src/pixie/fileformats/bmp.nim
@@ -23,6 +23,10 @@ proc decodeBmp*(data: string): Image =
   if compression notin [0, 3]:
     raise newException(PixieError, "Invalid BMP data format")
 
+  let channels = if bits == 32: 4 else: 3
+  if width * height * channels + offset > data.len:
+    raise newException(PixieError, "Invalid BMP data size")
+
   result = newImage(width, height)
 
   for y in 0 ..< result.height: