vfprintf typing problem

[David Miller]

From: "Carlos O'Donell" <carlos@systemhalted.org>
Date: Sat, 31 Mar 2012 22:10:44 -0400

> Does that make sense?

Yep.

> The check probably has to be:
> 
> if (retval > INT_MAX/10-digit)
>   return -1;
> retval *= 10;
> retal += digit;
> 
> That way you *know* the next two operations won't overflow, and either
> you exit or get another chance at looking at the next operation.

Ok, I'll let this patch cook in my build/testsuite runs overnight:

diff --git a/stdio-common/printf-parse.h b/stdio-common/printf-parse.h
index bcf914b..2038541 100644
--- a/stdio-common/printf-parse.h
+++ b/stdio-common/printf-parse.h
@@ -75,10 +75,12 @@ read_int (const UCHAR_T * *pstr)
 
   while (ISDIGIT (*++(*pstr)))
     {
-      retval *= 10;
-      if (retval > INT_MAX)
+      unsigned int digit = **pstr - L_('0');
+
+      if (retval > INT_MAX/10 - digit)
 	return -1;
-      retval += **pstr - L_('0');
+      retval *= 10;
+      retval += digit;
     }
 
   return (int) retval;