[Bug libc/14459] New: strtod integer and buffer overflows

["jsm28 at gcc dot gnu.org" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=14459

             Bug #: 14459
           Summary: strtod integer and buffer overflows
           Product: glibc
           Version: 2.16
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: unassigned@sourceware.org
        ReportedBy: jsm28@gcc.gnu.org
                CC: drepper.fsp@gmail.com
    Classification: Unclassified


strtod and related functions have integer overflow bugs resulting from the use
of "int" for internal variables and calculations where the actual values
involved may exceed the range of int.  These integer overflows can in turn
result in buffer overflow on the stack.  The following testcase illustrates
such a buffer overflow.  Testing a patch.  (I found this issue while working on
the fix for bug 3479.)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define EXPONENT "e-2147483649"
#define SIZE 214748364

int
main (void)
{
  char *p = malloc (1 + SIZE + sizeof (EXPONENT));
  if (p == NULL)
    {
      perror ("malloc");
      exit (EXIT_FAILURE);
    }
  p[0] = '1';
  memset (p + 1, '0', SIZE);
  memcpy (p + 1 + SIZE, EXPONENT, sizeof (EXPONENT));
  double d = strtod (p, NULL);
  printf ("%a\n", d);
  exit (EXIT_SUCCESS);
}

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