diff -up patch-2.7.6/lib/vasnprintf.c.me patch-2.7.6/lib/vasnprintf.c

--- patch-2.7.6/lib/vasnprintf.c.me	2018-11-26 14:02:03.401718842 +0100

+++ patch-2.7.6/lib/vasnprintf.c	2018-11-26 14:03:02.923913446 +0100

@@ -860,7 +860,9 @@ convert_to_decimal (mpn_t a, size_t extr

   size_t a_len = a.nlimbs;

   /* 0.03345 is slightly larger than log(2)/(9*log(10)).  */

   size_t c_len = 9 * ((size_t)(a_len * (GMP_LIMB_BITS * 0.03345f)) + 1);

-  char *c_ptr = (char *) malloc (xsum (c_len, extra_zeroes));

+  /* We need extra_zeroes bytes for zeroes, followed by c_len bytes for the

+     digits of a, followed by 1 byte for the terminating NUL.  */

+  char *c_ptr = (char *) malloc (xsum (xsum (extra_zeroes, c_len), 1));

   if (c_ptr != NULL)

     {

       char *d_ptr = c_ptr;