Add some slack at the end of large allocations when target SDK level < S.
This works around buggy applications that read a few bytes past the
end of their allocation, which would otherwise cause a segfault with
the concurrent Scudo change that aligns large allocations to the right.
Because the implementation of
android_set_application_target_sdk_version() lives in the linker,
we need to introduce a hook so that libc is notified when the target
SDK version changes.
Bug: 181344545
Change-Id: Id4be6645b94fad3f64ae48afd16c0154f1de448f
diff --git a/libc/bionic/libc_init_common.cpp b/libc/bionic/libc_init_common.cpp
index 01cd2e5..d9dcdc4 100644
--- a/libc/bionic/libc_init_common.cpp
+++ b/libc/bionic/libc_init_common.cpp
@@ -131,6 +131,14 @@
pthread_atfork(arc4random_fork_handler, _thread_arc4_unlock, _thread_arc4_unlock);
}
+extern "C" void scudo_malloc_set_add_large_allocation_slack(int add_slack);
+
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE void __libc_set_target_sdk_version(int target __unused) {
+#if defined(USE_SCUDO)
+ scudo_malloc_set_add_large_allocation_slack(target < __ANDROID_API_S__);
+#endif
+}
+
__noreturn static void __early_abort(int line) {
// We can't write to stdout or stderr because we're aborting before we've checked that
// it's safe for us to use those file descriptors. We probably can't strace either, so