Add some assertions demonstrating why cols*rows does not overflow

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@2873 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 10 insertions, 0 deletions

diff --git a/converter/other/bmptopnm.c b/converter/other/bmptopnm.c
index 13a5fb8d..54868364 100644
--- a/converter/other/bmptopnm.c
+++ b/converter/other/bmptopnm.c
@@ -695,6 +695,13 @@ bmpReadinfoheader(FILE *                 const ifP,
         *errorP = NULL;
         *bytesReadP = cInfoHeaderSize;
     }
+    /* Part of our anti-arithmetic overflow strategy is to make sure height
+       and width always fit in 16 bits, so they can be multiplied together.
+       This shouldn't be a problem, since they come from 16 bit fields in
+       the BMP info header.
+    */
+    assert(headerP->cols < (1<<16));
+    assert(headerP->rows < (1<<16));
 }
 
 
@@ -1204,6 +1211,9 @@ bmpReadraster(FILE *            const ifP,
         */
     unsigned char ** bmpRaster;
 
+    assert(cols < (1<<16));
+    assert(bytesPerRow < (1<<16));
+
     bmpRaster = allocBmpRaster(rows, bytesPerRow);
 
     *bytesReadP = 0;