runtime: in asan mode unregister root regions on free

CL 651755 introduced registration of root regions when allocating
memory. We also need to unregister that memory to avoid the leak
sanitizer accessing unmapped memory.

Issue #67833

Change-Id: I5d403d66e65a8a003492f4d79dad22d416fd8574
Reviewed-on: https://go-review.googlesource.com/c/go/+/659135
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: znkr

src/runtime/asan.go

@@ -64,6 +64,9 @@ func asanregisterglobals(addr unsafe.Pointer, n uintptr)
 //go:noescape
 func lsanregisterrootregion(addr unsafe.Pointer, n uintptr)
 
+//go:noescape
+func lsanunregisterrootregion(addr unsafe.Pointer, n uintptr)
+
 func lsandoleakcheck()
 
 // These are called from asan_GOARCH.s
@@ -74,4 +77,5 @@ func lsandoleakcheck()
 //go:cgo_import_static __asan_poison_go
 //go:cgo_import_static __asan_register_globals_go
 //go:cgo_import_static __lsan_register_root_region_go
+//go:cgo_import_static __lsan_unregister_root_region_go
 //go:cgo_import_static __lsan_do_leak_check_go

src/runtime/asan/asan.go

@@ -39,6 +39,10 @@ void __lsan_register_root_region_go(void *addr, uintptr_t sz) {
 	__lsan_register_root_region(addr, sz);
 }
 
+void __lsan_unregister_root_region_go(void *addr, uintptr_t sz) {
+	__lsan_unregister_root_region(addr, sz);
+}
+
 void __lsan_do_leak_check_go(void) {
 	__lsan_do_leak_check();
 }

src/runtime/asan0.go

@@ -22,4 +22,5 @@ func asanunpoison(addr unsafe.Pointer, sz uintptr)        { throw("asan") }
 func asanpoison(addr unsafe.Pointer, sz uintptr)          { throw("asan") }
 func asanregisterglobals(addr unsafe.Pointer, sz uintptr) { throw("asan") }
 func lsanregisterrootregion(unsafe.Pointer, uintptr)      { throw("asan") }
+func lsanunregisterrootregion(unsafe.Pointer, uintptr)    { throw("asan") }
 func lsandoleakcheck()                                    { throw("asan") }

src/runtime/asan_amd64.s

@@ -77,6 +77,14 @@ TEXT	runtime·lsanregisterrootregion(SB), NOSPLIT, $0-16
 	MOVQ	$__lsan_register_root_region_go(SB), AX
 	JMP	asancall<>(SB)
 
+// func runtime·lsanunregisterrootregion(addr unsafe.Pointer, n uintptr)
+TEXT	runtime·lsanunregisterrootregion(SB), NOSPLIT, $0-16
+	MOVQ	addr+0(FP), RARG0
+	MOVQ	n+8(FP), RARG1
+	// void __lsan_unregister_root_region_go(void *addr, uintptr_t sz)
+	MOVQ	$__lsan_unregister_root_region_go(SB), AX
+	JMP	asancall<>(SB)
+
 // func runtime·lsandoleakcheck()
 TEXT	runtime·lsandoleakcheck(SB), NOSPLIT, $0-0
 	// void __lsan_do_leak_check_go(void);

src/runtime/asan_arm64.s

@@ -66,6 +66,14 @@ TEXT	runtime·lsanregisterrootregion(SB), NOSPLIT, $0-16
 	MOVD	$__lsan_register_root_region_go(SB), FARG
 	JMP	asancall<>(SB)
 
+// func runtime·lsanunregisterrootregion(addr unsafe.Pointer, n uintptr)
+TEXT	runtime·lsanunregisterrootregion(SB), NOSPLIT, $0-16
+	MOVD	addr+0(FP), RARG0
+	MOVD	n+8(FP), RARG1
+	// void __lsan_unregister_root_region_go(void *addr, uintptr_t n);
+	MOVD	$__lsan_unregister_root_region_go(SB), FARG
+	JMP	asancall<>(SB)
+
 // func runtime·lsandoleakcheck()
 TEXT	runtime·lsandoleakcheck(SB), NOSPLIT, $0-0
 	// void __lsan_do_leak_check_go(void);

src/runtime/asan_loong64.s

@@ -66,6 +66,14 @@ TEXT	runtime·lsanregisterrootregion(SB), NOSPLIT, $0-16
 	MOVV	$__lsan_register_root_region_go(SB), FARG
 	JMP	asancall<>(SB)
 
+// func runtime·lsanunregisterrootregion(addr unsafe.Pointer, n uintptr)
+TEXT	runtime·lsanunregisterrootregion(SB), NOSPLIT, $0-16
+	MOVV	addr+0(FP), RARG0
+	MOVV	n+8(FP), RARG1
+	// void __lsan_unregister_root_region_go(void *addr, uintptr_t n);
+	MOVV	$__lsan_unregister_root_region_go(SB), FARG
+	JMP	asancall<>(SB)
+
 // func runtime·lsandoleakcheck()
 TEXT	runtime·lsandoleakcheck(SB), NOSPLIT, $0-0
 	// void __lsan_do_leak_check_go(void);

src/runtime/asan_ppc64le.s

@@ -66,6 +66,14 @@ TEXT	runtime·lsanregisterrootregion(SB),NOSPLIT|NOFRAME,$0-16
 	MOVD	$__lsan_register_root_region_go(SB), FARG
 	BR	asancall<>(SB)
 
+// func runtime·lsanunregisterrootregion(addr unsafe.Pointer, n uintptr)
+TEXT	runtime·lsanunregisterrootregion(SB),NOSPLIT|NOFRAME,$0-16
+	MOVD	addr+0(FP), RARG0
+	MOVD	n+8(FP), RARG1
+	// void __lsan_unregister_root_region_go(void *addr, uintptr_t n);
+	MOVD	$__lsan_unregister_root_region_go(SB), FARG
+	BR	asancall<>(SB)
+
 // func runtime·lsandoleakcheck()
 TEXT	runtime·lsandoleakcheck(SB), NOSPLIT|NOFRAME, $0-0
 	// void __lsan_do_leak_check_go(void);

src/runtime/asan_riscv64.s

@@ -60,6 +60,14 @@ TEXT	runtime·lsanregisterrootregion(SB), NOSPLIT, $0-16
 	MOV	$__lsan_register_root_region_go(SB), X14
 	JMP	asancall<>(SB)
 
+// func runtime·lsanunregisterrootregion(addr unsafe.Pointer, n uintptr)
+TEXT	runtime·lsanunregisterrootregion(SB), NOSPLIT, $0-16
+	MOV	addr+0(FP), X10
+	MOV	n+8(FP), X11
+	// void __lsan_unregister_root_region_go(void *addr, uintptr_t n);
+	MOV	$__lsan_unregister_root_region_go(SB), X14
+	JMP	asancall<>(SB)
+
 // func runtime·lsandoleakcheck()
 TEXT	runtime·lsandoleakcheck(SB), NOSPLIT, $0-0
 	// void __lsan_do_leak_check_go(void);

src/runtime/mem.go

@@ -119,6 +119,13 @@ func sysHugePageCollapse(v unsafe.Pointer, n uintptr) {
 //
 //go:nosplit
 func sysFree(v unsafe.Pointer, n uintptr, sysStat *sysMemStat) {
+	// When using ASAN leak detection, the memory being freed is
+	// known by the sanitizer. We need to unregister it so it's
+	// not accessed by it.
+	if asanenabled {
+		lsanunregisterrootregion(v, n)
+	}
+
 	sysStat.add(-int64(n))
 	gcController.mappedReady.Add(-int64(n))
 	sysFreeOS(v, n)