From 287d9bc80e1afdfd48a451864ec4ff5dd3955a1c Mon Sep 17 00:00:00 2001
From: Ryan Oldenburg <ryan@guzba.com>
Date: Mon, 29 May 2023 00:10:23 -0500
Subject: [PATCH] fix bounds check

---
 src/pixie/fileformats/ppm.nim | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/pixie/fileformats/ppm.nim b/src/pixie/fileformats/ppm.nim
index c81e6f7..4bba3d4 100644
--- a/src/pixie/fileformats/ppm.nim
+++ b/src/pixie/fileformats/ppm.nim
@@ -15,14 +15,13 @@ template failInvalid() =
 proc decodeHeader(
   data: ptr UncheckedArray[uint8], len: int
 ): PpmHeader {.raises: [PixieError].} =
-  if len <= 10: # Each part + whitespace
-    raise newException(PixieError, "Invalid PPM file header")
-
   var
     commentMode, readWhitespace: bool
     i, readFields: int
     field: string
   while readFields < 4:
+    if i >= len:
+      raise newException(PixieError, "Invalid PPM file header")
     let c = data[i].char
     if c == '#':
       commentMode = true