if (!p)
return instance.Allocate(size, 8, stack, FROM_MALLOC, true);
if (size == 0) {
- instance.Deallocate(p, 0, stack, FROM_MALLOC);
- return nullptr;
+ if (flags()->allocator_frees_and_returns_null_on_realloc_zero) {
+ instance.Deallocate(p, 0, stack, FROM_MALLOC);
+ return nullptr;
+ }
+ // Allocate a size of 1 if we shouldn't free() on Realloc to 0
+ size = 1;
}
return instance.Reallocate(p, size, stack);
}
"(WARNING: USE AT YOUR OWN RISK!)")
ASAN_FLAG(bool, use_odr_indicator, false,
"Use special ODR indicator symbol for ODR violation detection")
+ASAN_FLAG(bool, allocator_frees_and_returns_null_on_realloc_zero, true,
+ "realloc(p, 0) is equivalent to free(p) by default (Same as the "
+ "POSIX standard). If set to false, realloc(p, 0) will return a "
+ "pointer to an allocated space which can not be used.")
--- /dev/null
+// RUN: %clangxx_asan -O0 %s -o %t
+// Default is true (free on realloc to 0 size)
+// RUN: %run %t 2>&1 | FileCheck %s
+// RUN: %env_asan_opts=allocator_frees_and_returns_null_on_realloc_zero=true %run %t 2>&1 | FileCheck %s
+// RUN: %env_asan_opts=allocator_frees_and_returns_null_on_realloc_zero=false %run %t 2>&1 | FileCheck %s --check-prefix=NO-FREE
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+ void *p = malloc(42);
+ p = realloc(p, 0);
+ if (p) {
+ // NO-FREE: Allocated something on realloc(p, 0)
+ fprintf(stderr, "Allocated something on realloc(p, 0)\n");
+ } else {
+ // CHECK: realloc(p, 0) returned nullptr
+ fprintf(stderr, "realloc(p, 0) returned nullptr\n");
+ }
+ free(p);
+}