1 files changed, 50 insertions, 0 deletions
diff --git a/alloc.c b/alloc.c
new file mode 100644
index 0000000..8ec0a7e
--- /dev/null
+++ b/alloc.c
@@ -0,0 +1,50 @@
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+#include "byte.h"
+#include "alloc.h"
+
+#define ALIGNMENT 16 /* XXX: assuming that this alignment is enough */
+#define SPACE 4096   /* must be multiple of ALIGNMENT */
+
+typedef union { char irrelevant[ALIGNMENT]; double d; } aligned;
+static aligned realspace[SPACE / ALIGNMENT];
+#define space ((char *) realspace)
+static unsigned int avail = SPACE; /* multiple of ALIGNMENT; 0<=avail<=SPACE */
+
+/*@null@*//*@out@*/char *alloc(unsigned int n) {
+  char *x;
+
+/* Guninski exploit + patch from Qualys (CVE-2005-1513) */
+
+  if (n >= (INT_MAX >> 3)) {
+    errno = ENOMEM;
+    return 0;
+  }
+
+  n = ALIGNMENT + n - (n & (ALIGNMENT - 1)); /* XXX: could overflow */
+  if (n <= avail) { avail -= n; return space + avail; }
+  x = malloc(n);
+  if (!x) errno = ENOMEM;
+  return x;
+}
+
+void alloc_free(char *x) 
+{
+  if (x >= space)
+    if (x < space + SPACE)
+      return; /* XXX: assuming that pointers are flat */
+  free(x);
+}
+
+int alloc_re(char **x,unsigned int m,unsigned int n) 
+{
+  char *y;
+
+  y = alloc(n);
+  if (!y) return 0;
+  byte_copy(y,m,*x);
+  qfree(*x);
+  *x = y;
+  return 1;
+}