https://github.com/ImageMagick/ImageMagick/issues/1614

diff --git a/coders/pnm.c b/coders/pnm.c
index 72674011127f8b99702c55eba4865efef45c14b8..fd231ef31e3732535a19c228f5cc24d29065813d 100644 (file)
--- a/coders/pnm.c
+++ b/coders/pnm.c
@@ -1760,7 +1760,7 @@ static MagickBooleanType WritePNMImage(const ImageInfo *image_info,Image *image,
           {
             *q++=(unsigned char) (GetPixelLuma(image,p) >= (QuantumRange/2.0) ?
               '0' : '1');
-            if ((q-pixels+1) >= (ssize_t) sizeof(pixels))
+            if ((q-pixels+2) >= (ssize_t) sizeof(pixels))
               {
                 *q++='\n';
                 (void) WriteBlob(image,q-pixels,pixels);