commit 761fdf919dcf7fa698cf41c0515abca3a3143dca
author Florian Mayer <fmayer@google.com> Mon Sep 16 15:13:39 2024 -0700
committer Florian Mayer <fmayer@google.com> Tue Sep 17 12:17:47 2024 -0700
tree 1c007814ad1690e0d754245d14d1b20fa1961d30
parent 312e74ad0ab3e007df8b2c39ad7a8e50a8148523

[HWASan] init auxv for pagesize in hwasan_init_static

Test: run snapuserd
Bug: 366043544
Change-Id: Ia9c883fd750abc04df3ff01b469dfaf13f945a03

libc/bionic/libc_init_static.cpp

diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index 2227856..7c46113 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -421,12 +421,11 @@
 }
 
 __attribute__((no_sanitize("memtag"))) __noreturn static void __real_libc_init(
-    void* raw_args, void (*onexit)(void) __unused, int (*slingshot)(int, char**, char**),
-    structors_array_t const* const structors, bionic_tcb* temp_tcb) {
+    KernelArgumentBlock& args, void* raw_args, void (*onexit)(void) __unused,
+    int (*slingshot)(int, char**, char**), structors_array_t const* const structors,
+    bionic_tcb* temp_tcb) {
   BIONIC_STOP_UNWIND;
 
-  // Initialize TLS early so system calls and errno work.
-  KernelArgumentBlock args(raw_args);
   __libc_init_main_thread_early(args, temp_tcb);
   __libc_init_main_thread_late();
   __libc_init_globals();
@@ -479,17 +478,19 @@
   bionic_tcb temp_tcb __attribute__((uninitialized));
   __builtin_memset_inline(&temp_tcb, 0, sizeof(temp_tcb));
 
+  KernelArgumentBlock args(raw_args);
 #if __has_feature(hwaddress_sanitizer)
   // Install main thread TLS early. It will be initialized later in __libc_init_main_thread. For now
-  // all we need is access to TLS_SLOT_SANITIZER.
+  // all we need is access to TLS_SLOT_SANITIZER and read auxval for the page size.
   __set_tls(&temp_tcb.tls_slot(0));
+  __libc_shared_globals()->auxv = args.auxv;
   // Initialize HWASan enough to run instrumented code. This sets up TLS_SLOT_SANITIZER, among other
   // things.
   __hwasan_init_static();
   // We are ready to run HWASan-instrumented code, proceed with libc initialization...
 #endif
 
-  __real_libc_init(raw_args, onexit, slingshot, structors, &temp_tcb);
+  __real_libc_init(args, raw_args, onexit, slingshot, structors, &temp_tcb);
 }
 
 static int g_target_sdk_version{__ANDROID_API__};

libc/private/KernelArgumentBlock.h

diff --git a/libc/private/KernelArgumentBlock.h b/libc/private/KernelArgumentBlock.h
index ee28d69..e1f655a 100644
--- a/libc/private/KernelArgumentBlock.h
+++ b/libc/private/KernelArgumentBlock.h
@@ -29,7 +29,7 @@
 // constituents for easy access.
 class KernelArgumentBlock {
  public:
-  explicit KernelArgumentBlock(void* raw_args) {
+  __attribute__((no_sanitize("hwaddress"))) explicit KernelArgumentBlock(void* raw_args) {
     uintptr_t* args = reinterpret_cast<uintptr_t*>(raw_args);
     argc = static_cast<int>(*args);
     argv = reinterpret_cast<char**>(args + 1);
@@ -48,7 +48,7 @@
 
   // Similar to ::getauxval but doesn't require the libc global variables to be set up,
   // so it's safe to call this really early on.
-  unsigned long getauxval(unsigned long type) {
+  __attribute__((no_sanitize("hwaddress"))) unsigned long getauxval(unsigned long type) {
     for (ElfW(auxv_t)* v = auxv; v->a_type != AT_NULL; ++v) {
       if (v->a_type == type) {
         return v->a_un.a_val;