Frida cmplog fail fast (#914)

* Changes to remove binaries from frida_mode

* Changes to make cmplog fail fast

Co-authored-by: Your Name <you@example.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/frida_mode/src/cmplog/cmplog.c b/frida_mode/src/cmplog/cmplog.c
index 84412c0b..3fab1951 100644
--- a/frida_mode/src/cmplog/cmplog.c
+++ b/frida_mode/src/cmplog/cmplog.c
@@ -4,6 +4,8 @@
 
 #include "util.h"
 
+#define DEFAULT_MMAP_MIN_ADDR (32UL << 10)
+
 extern struct cmp_map *__afl_cmp_map;
 
 static GArray *cmplog_ranges = NULL;
@@ -55,6 +57,16 @@ gboolean cmplog_is_readable(void *addr, size_t size) {
 
   if (cmplog_ranges == NULL) FATAL("CMPLOG not initialized");
 
+  /*
+   * The Linux kernel prevents mmap from allocating from the very bottom of the
+   * address space to mitigate NULL pointer dereference attacks. The exact size
+   * is set by sysctl by setting mmap_min_addr and 64k is suggested on most
+   * platforms with 32k on ARM systems. We therefore fail fast if the address
+   * is lower than this. This should avoid some overhead when functions are
+   * called where one of the parameters is a size, or a some other small value.
+   */
+  if (GPOINTER_TO_SIZE(addr) < DEFAULT_MMAP_MIN_ADDR) { return false; }
+
   GumAddress inner_base = GUM_ADDRESS(addr);
   GumAddress inner_limit = inner_base + size;