linker: add android_use_fallback_allocator.
Add a function to enable a fallback allocator to use for crash handling
in a signal handler.
Bug: http://b/34684590
Test: crasher PR_SET_NO_NEW_PRIVS
Change-Id: Ifa5de636164f34b8cb2fdec4471c20f8516b6dbe
diff --git a/linker/linker_memory.cpp b/linker/linker_memory.cpp
index 1892d02..918adb0 100644
--- a/linker/linker_memory.cpp
+++ b/linker/linker_memory.cpp
@@ -17,22 +17,51 @@
#include "linker_allocator.h"
#include <stdlib.h>
+#include <sys/cdefs.h>
+#include <unistd.h>
+
+#include "private/libc_logging.h"
static LinkerMemoryAllocator g_linker_allocator;
+static pid_t fallback_tid = 0;
+
+// Used by libdebuggerd_handler to switch allocators during a crash dump, in
+// case the linker heap is corrupted. Do not use this function.
+extern "C" void __linker_use_fallback_allocator() {
+ if (fallback_tid != 0) {
+ __libc_format_log(ANDROID_LOG_ERROR, "libc",
+ "attempted to set fallback allocator multiple times");
+ return;
+ }
+
+ fallback_tid = gettid();
+}
+
+static LinkerMemoryAllocator& get_fallback_allocator() {
+ static LinkerMemoryAllocator fallback_allocator;
+ return fallback_allocator;
+}
+
+static LinkerMemoryAllocator& get_allocator() {
+ if (__predict_false(fallback_tid) && __predict_false(gettid() == fallback_tid)) {
+ return get_fallback_allocator();
+ }
+ return g_linker_allocator;
+}
void* malloc(size_t byte_count) {
- return g_linker_allocator.alloc(byte_count);
+ return get_allocator().alloc(byte_count);
}
void* calloc(size_t item_count, size_t item_size) {
- return g_linker_allocator.alloc(item_count*item_size);
+ return get_allocator().alloc(item_count*item_size);
}
void* realloc(void* p, size_t byte_count) {
- return g_linker_allocator.realloc(p, byte_count);
+ return get_allocator().realloc(p, byte_count);
}
void free(void* ptr) {
- g_linker_allocator.free(ptr);
+ get_allocator().free(ptr);
}