Add tagged pointers to bionic.
This patch introduces tagged pointers to bionic. We add a static tag to
all pointers on arm64 compatible platforms (needs requisite
top-byte-ignore hardware feature and relevant kernel patches).
We dynamically detect TBI-compatible devices (a device with the TBI feature and
kernel support) at process start time, and insert an implementation-dependent
tag into the top byte of the pointer for all heap allocations. We then check
that the tag has not been truncated when deallocating the memory.
If an application incorrectly writes to the top byte of the pointer, we
terminate the process at time of detection. This will allow MTE-incompatible
applications to be caught early.
Bug: 135754954
Bug: 147147490
Test: cd bionic && atest .
Change-Id: Ie424325ba1e3c4443040ac265aeaa28d9e405d28
diff --git a/libc/private/bionic_globals.h b/libc/private/bionic_globals.h
index 7f1b3d9..8997ceb 100644
--- a/libc/private/bionic_globals.h
+++ b/libc/private/bionic_globals.h
@@ -44,6 +44,7 @@
struct libc_globals {
vdso_entry vdso[VDSO_END];
long setjmp_cookie;
+ uintptr_t heap_pointer_tag;
// In order to allow a complete switch between dispatch tables without
// the need for copying each function by function in the structure,