krb5 commit: Fix signed overflow check in k5_ucs2s_to_utf8s

[Greg Hudson]

https://github.com/krb5/krb5/commit/7506becc0ac70915050e097d673e7647b99347fc
commit 7506becc0ac70915050e097d673e7647b99347fc
Author: Greg Hudson <ghudson at mit.edu>
Date:   Thu Dec 20 14:20:37 2012 -0500

    Fix signed overflow check in k5_ucs2s_to_utf8s
    
    Signed overflow must be checked before it happens, since modern
    versions of gcc will optimize out checks of the result.  Reported by
    Nickolai Zeldovich <nickolai at csail.mit.edu>.
    
    ticket: 7511

 src/util/support/utf8_conv.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/src/util/support/utf8_conv.c b/src/util/support/utf8_conv.c
index 6e7c588..d580bbc 100644
--- a/src/util/support/utf8_conv.c
+++ b/src/util/support/utf8_conv.c
@@ -276,10 +276,8 @@ k5_ucs2s_to_utf8s(char *utf8str, const krb5_ucs2 *ucs2str,
 #endif
 
             n = krb5int_ucs2_to_utf8(ch, NULL);
-            if (n < 1)
+            if (n < 1 || n > INT_MAX - len)
                 return -1;
-            if (len + n < len)
-                return -1; /* overflow */
             len += n;
         }