commit 296bd992b7918dcf27a1d67d16edeccececa0887
author Elliott Hughes <enh@google.com> Sat Jan 18 05:40:45 2025 -0800
committer Gerrit Code Review <noreply-gerritcodereview@google.com> Sat Jan 18 05:40:45 2025 -0800
tree 568519f3e185417c5a5ac74b205a282c91a4ccaf
parent d5e064d698f10f6419e30fc5f3b162f0b4a6cdce
parent ec79de0907aeecfe4cb94cc1fb0510ba148eb8c5

Merge "Skip rather than reject invalid ELF notes for existing apps." into main

libc/bionic/heap_tagging.cpp

diff --git a/libc/bionic/heap_tagging.cpp b/libc/bionic/heap_tagging.cpp
index 6741be3..c731970 100644
--- a/libc/bionic/heap_tagging.cpp
+++ b/libc/bionic/heap_tagging.cpp
@@ -123,6 +123,7 @@
         }
         atomic_store(&__libc_memtag_stack, false);
         atomic_store(&globals->memtag, false);
+        atomic_store(&__libc_shared_globals()->memtag_currently_on, false);
       });
 
       if (heap_tagging_level != M_HEAP_TAGGING_LEVEL_TBI) {

libc/bionic/libc_init_mte.cpp

diff --git a/libc/bionic/libc_init_mte.cpp b/libc/bionic/libc_init_mte.cpp
index 3c8ef7d..eda2eec 100644
--- a/libc/bionic/libc_init_mte.cpp
+++ b/libc/bionic/libc_init_mte.cpp
@@ -273,6 +273,7 @@
     if (prctl(PR_SET_TAGGED_ADDR_CTRL, prctl_arg | PR_MTE_TCF_SYNC, 0, 0, 0) == 0 ||
         prctl(PR_SET_TAGGED_ADDR_CTRL, prctl_arg, 0, 0, 0) == 0) {
       __libc_shared_globals()->initial_heap_tagging_level = level;
+      atomic_store(&__libc_shared_globals()->memtag_currently_on, true);
 
       struct sigaction action = {};
       action.sa_flags = SA_SIGINFO | SA_RESTART;
@@ -320,6 +321,5 @@
 #endif  // __aarch64__
 
 bool __libc_mte_enabled() {
-  HeapTaggingLevel lvl = __libc_shared_globals()->initial_heap_tagging_level;
-  return lvl == M_HEAP_TAGGING_LEVEL_SYNC || lvl == M_HEAP_TAGGING_LEVEL_ASYNC;
+  return atomic_load(&__libc_shared_globals()->memtag_currently_on);
 }

libc/private/bionic_globals.h

diff --git a/libc/private/bionic_globals.h b/libc/private/bionic_globals.h
index cd6dca9..77ac21f 100644
--- a/libc/private/bionic_globals.h
+++ b/libc/private/bionic_globals.h
@@ -146,6 +146,7 @@
   size_t scudo_stack_depot_size = 0;
 
   HeapTaggingLevel initial_heap_tagging_level = M_HEAP_TAGGING_LEVEL_NONE;
+  _Atomic(bool) memtag_currently_on = false;
   // See comments for __libc_memtag_stack / __libc_memtag_stack_abi above.
   bool initial_memtag_stack = false;
   bool initial_memtag_stack_abi = false;

linker/linker.cpp

diff --git a/linker/linker.cpp b/linker/linker.cpp
index 8f78915..0b829b3 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -2369,8 +2369,10 @@
         }
         void* tls_block = get_tls_block_for_this_thread(tls_module, /*should_alloc=*/true);
         *symbol = static_cast<char*>(tls_block) + sym->st_value;
-      } else {
+      } else if (__libc_mte_enabled()) {
         *symbol = get_tagged_address(reinterpret_cast<void*>(found->resolve_symbol_address(sym)));
+      } else {
+        *symbol = reinterpret_cast<void*>(found->resolve_symbol_address(sym));
       }
       failure_guard.Disable();
       LD_LOG(kLogDlsym,