fix arithmetic overflows

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@4177 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 20 insertions, 17 deletions

diff --git a/converter/pbm/ybmtopbm.c b/converter/pbm/ybmtopbm.c
index 2a429086..36f2dee7 100644
--- a/converter/pbm/ybmtopbm.c
+++ b/converter/pbm/ybmtopbm.c
@@ -19,45 +19,48 @@ static short const ybmMagic = ( ( '!' << 8 ) | '!' );
 
 
 static void
-getinit(FILE *  const ifP,
-        short * const colsP,
-        short * const rowsP,
-        short * const depthP) {
+getinit(FILE *         const ifP,
+        unsigned int * const colsP,
+        unsigned int * const rowsP,
+        int *          const depthP) {
 
-    short magic;
+    short int magic;
+    short int cols, rows;
     int rc;
 
     rc = pm_readbigshort(ifP, &magic);
     if (rc == -1)
         pm_error("EOF / read error");
-
-    if (magic != ybmMagic)
+    else if (magic != ybmMagic)
         pm_error("bad magic number in YBM file");
 
-    rc = pm_readbigshort(ifP, colsP);
+    rc = pm_readbigshort(ifP, &cols);
     if (rc == -1 )
         pm_error("EOF / read error");
+    else if (cols <= 0)
+        pm_error("invalid width value in YBM file");
 
-    rc = pm_readbigshort(ifP, rowsP);
+    rc = pm_readbigshort(ifP, &rows);
     if (rc == -1)
         pm_error("EOF / read error");
+    else if (rows <= 0)
+        pm_error("invalid height value in YBM file");
 
+    *colsP = (unsigned int) cols;
+    *rowsP = (unsigned int) rows;
     *depthP = 1;
 }
 
 
 
-
-
-
 int
 main(int argc, const char * argv[]) {
 
     FILE * ifP;
     bit * bitrow;
-    short rows, cols;
+    unsigned int rows, cols;
     unsigned int row;
-    short depth;
+    int depth;
     const char * inputFile;
 
     pm_proginit(&argc, argv);
@@ -76,8 +79,8 @@ main(int argc, const char * argv[]) {
 
     getinit(ifP, &cols, &rows, &depth);
     if (depth != 1)
-        pm_error("YBM file has depth of %u, must be 1", (unsigned)depth);
-    
+        pm_error("YBM file has depth of %u, must be 1", (unsigned int) depth);
+
     pbm_writepbminit(stdout, cols, rows, 0);
 
     bitrow = pbm_allocrow_packed(cols + 8);
@@ -92,7 +95,7 @@ main(int argc, const char * argv[]) {
         for (i = 0; i < itemCt; ++i) {
             short int item;
             pm_readbigshort(ifP, &item);
-            itemrow[i] = (uint16_t) item; 
+            itemrow[i] = (uint16_t) item;
         }
 
         for (i = 0; i < pbm_packed_bytes(cols); ++i)