mirror/naiveproxy
1
0
Fork 0
mirror of https://github.com/klzgrad/naiveproxy.git synced 2025-04-03 13:53:37 +03:00
Code Issues Projects Releases Wiki Activity

musl: allocator: Avoid deadlock in pthread_atfork

Browse source 
Musl 1.2.3 and before call malloc() in pthread_atfork(),
which may result in a deadlock:

    PartitionRoot::EnableThreadCacheIfSupported()
      ::partition_alloc::internal::ScopedGuard guard{lock_};
      ThreadCache::Create(this);
        ThreadCache::ThreadCache()
          PlatformThread::CurrentId()
            InitAtFork::InitAtFork()
              pthread_atfork()
                malloc()
                  ShimMalloc()
                    PartitionAllocFunctionsInternal::Malloc()
                      PartitionRoot::AllocInternal()
                        PartitionRoot::AllocInternalNoHooks()
                          PartitionRoot::RawAlloc()
                            ::partition_alloc::internal::ScopedGuard guard{internal::PartitionRootLock(this)};
This commit is contained in:
klzgrad 2025-02-08 19:57:01 +08:00
parent de31237db8
commit f25dc0d11d
2 changed files with 39 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

19
src/base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/threading/platform_thread_posix.cc
View file

@ -28,6 +28,10 @@
#include <zircon/process.h>
#endif
#if defined(__MUSL__)
#include "partition_alloc/shim/allocator_shim.h"
#endif
namespace partition_alloc::internal::base {
#if PA_BUILDFLAG(IS_LINUX) || PA_BUILDFLAG(IS_CHROMEOS)
@ -59,7 +63,22 @@ thread_local bool g_is_main_thread = true;
class InitAtFork {
public:
InitAtFork() {
#if defined(__MUSL__)
allocator_shim::AllocatorDispatch d =
*allocator_shim::GetAllocatorDispatchChainHeadForTesting();
d.alloc_function = +[](size_t size, void*) -> void* {
// The size of the scratch fits struct atfork_funcs in Musl pthread_atfork.c.
static char scratch[5 * sizeof(void*)];
return size != sizeof(scratch) ? nullptr : scratch;
};
allocator_shim::InsertAllocatorDispatch(&d);
#endif
pthread_atfork(nullptr, nullptr, internal::InvalidateTidCache);
#if defined(__MUSL__)
allocator_shim::RemoveAllocatorDispatchForTesting(&d);
#endif
}
};

20
src/base/allocator/partition_allocator/src/partition_alloc/partition_root.cc
View file

@ -51,6 +51,10 @@
#endif // PA_CONFIG(ENABLE_SHADOW_METADATA)
#endif // PA_BUILDFLAG(IS_LINUX) || PA_BUILDFLAG(IS_CHROMEOS)
#if defined(__MUSL__)
#include "partition_alloc/shim/allocator_shim.h"
#endif
namespace partition_alloc::internal {
#if PA_BUILDFLAG(RECORD_ALLOC_INFO)
@ -319,9 +323,25 @@ void PartitionAllocMallocInitOnce() {
// However, no perfect solution really exists to make threads + fork()
// cooperate, but deadlocks are real (and fork() is used in DEATH_TEST()s),
// and other malloc() implementations use the same techniques.
#if defined(__MUSL__)
allocator_shim::AllocatorDispatch d =
*allocator_shim::GetAllocatorDispatchChainHeadForTesting();
d.alloc_function = +[](size_t size, void*) -> void* {
// The size of the scratch fits struct atfork_funcs in Musl pthread_atfork.c.
static char scratch[5 * sizeof(void*)];
return size != sizeof(scratch) ? nullptr : scratch;
};
allocator_shim::InsertAllocatorDispatch(&d);
#endif
int err =
pthread_atfork(BeforeForkInParent, AfterForkInParent, AfterForkInChild);
PA_CHECK(err == 0);
#if defined(__MUSL__)
allocator_shim::RemoveAllocatorDispatchForTesting(&d);
#endif
#endif // PA_BUILDFLAG(IS_LINUX) || PA_BUILDFLAG(IS_CHROMEOS)
}