From a29c5e9e66c1ba2b7d6b292430898e9ae7598e68 Mon Sep 17 00:00:00 2001 From: Simon Butcher Date: Thu, 2 Feb 2017 08:46:53 +0000 Subject: [PATCH] Add comment to integer overflow fix in base64.c Adds clarifying comment to the integer overflow fix in base64.c --- library/base64.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/library/base64.c b/library/base64.c index 305afc57b..f06b57b31 100644 --- a/library/base64.c +++ b/library/base64.c @@ -192,6 +192,10 @@ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen, return( 0 ); } + /* The following expression is to calculate the following formula without + * risk of integer overflow in n: + * n = ( ( n * 6 ) + 7 ) >> 3; + */ n = ( 6 * ( n >> 3 ) ) + ( ( 6 * ( n & 0x7 ) + 7 ) >> 3 ); n -= j;