diff options
author | Jonathan Wakely <jwakely@redhat.com> | 2022-06-08 10:43:57 +0100 |
---|---|---|
committer | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2022-07-21 09:13:08 +0200 |
commit | ade3197134cc9ed2b7e589a7b58c73110ae13f1c (patch) | |
tree | 68a9dcbd2db2711c8815b9d77d9733ae18856efd /libstdc++-v3 | |
parent | 7f596e4314cbd496f90d16a91962141a418558af (diff) |
libstdc++: Fix lifetime bugs for non-TLS eh_globals [PR105880]
This ensures that the single-threaded fallback buffer eh_globals is not
destroyed during program termination, using the same immortalization
technique used for error category objects.
Also ensure that init._M_init can still be read after init has been
destroyed, by making it a static data member.
libstdc++-v3/ChangeLog:
PR libstdc++/105880
* libsupc++/eh_globals.cc (eh_globals): Ensure constant init and
prevent destruction during termination.
(__eh_globals_init::_M_init): Replace with static member _S_init.
(__cxxabiv1::__cxa_get_globals_fast): Update.
(__cxxabiv1::__cxa_get_globals): Likewise.
(cherry picked from commit 1e65f2ed99024f23c56f7b6a961898bcaa882a92)
Diffstat (limited to 'libstdc++-v3')
-rw-r--r-- | libstdc++-v3/libsupc++/eh_globals.cc | 51 |
1 files changed, 37 insertions, 14 deletions
diff --git a/libstdc++-v3/libsupc++/eh_globals.cc b/libstdc++-v3/libsupc++/eh_globals.cc index 3a003b89edf..768425c0f40 100644 --- a/libstdc++-v3/libsupc++/eh_globals.cc +++ b/libstdc++-v3/libsupc++/eh_globals.cc @@ -64,8 +64,26 @@ __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW #else -// Single-threaded fallback buffer. -static __cxa_eh_globals eh_globals; +#if __has_cpp_attribute(clang::require_constant_initialization) +# define __constinit [[clang::require_constant_initialization]] +#endif + +namespace +{ + struct constant_init + { + union { + unsigned char unused; + __cxa_eh_globals obj; + }; + constexpr constant_init() : obj() { } + + ~constant_init() { /* do nothing, union member is not destroyed */ } + }; + + // Single-threaded fallback buffer. + __constinit constant_init eh_globals; +} #if __GTHREADS @@ -90,32 +108,37 @@ eh_globals_dtor(void* ptr) struct __eh_globals_init { __gthread_key_t _M_key; - bool _M_init; + static bool _S_init; - __eh_globals_init() : _M_init(false) - { + __eh_globals_init() + { if (__gthread_active_p()) - _M_init = __gthread_key_create(&_M_key, eh_globals_dtor) == 0; + _S_init = __gthread_key_create(&_M_key, eh_globals_dtor) == 0; } ~__eh_globals_init() { - if (_M_init) + if (_S_init) __gthread_key_delete(_M_key); - _M_init = false; + _S_init = false; } + + __eh_globals_init(const __eh_globals_init&) = delete; + __eh_globals_init& operator=(const __eh_globals_init&) = delete; }; +bool __eh_globals_init::_S_init = false; + static __eh_globals_init init; extern "C" __cxa_eh_globals* __cxxabiv1::__cxa_get_globals_fast() _GLIBCXX_NOTHROW { __cxa_eh_globals* g; - if (init._M_init) + if (init._S_init) g = static_cast<__cxa_eh_globals*>(__gthread_getspecific(init._M_key)); else - g = &eh_globals; + g = &eh_globals.obj; return g; } @@ -123,7 +146,7 @@ extern "C" __cxa_eh_globals* __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW { __cxa_eh_globals* g; - if (init._M_init) + if (init._S_init) { g = static_cast<__cxa_eh_globals*>(__gthread_getspecific(init._M_key)); if (!g) @@ -140,7 +163,7 @@ __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW } } else - g = &eh_globals; + g = &eh_globals.obj; return g; } @@ -148,11 +171,11 @@ __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW extern "C" __cxa_eh_globals* __cxxabiv1::__cxa_get_globals_fast() _GLIBCXX_NOTHROW -{ return &eh_globals; } +{ return &eh_globals.obj; } extern "C" __cxa_eh_globals* __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW -{ return &eh_globals; } +{ return &eh_globals.obj; } #endif |