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https://github.com/bdwgc/bdwgc/issues/783
https://github.com/bdwgc/bdwgc/issues/802
https://github.com/bdwgc/bdwgc/commit/910b4f008f3bcb436a23a2d5f9784e5dd9ab66cd
https://github.com/bdwgc/bdwgc/commit/1058994bc264dd99a7b6d3caefe0c129bfbd1fb7
https://github.com/bdwgc/bdwgc/commit/73fdfdaf45fd35993c7f9e051875147ca39438c4
From 910b4f008f3bcb436a23a2d5f9784e5dd9ab66cd Mon Sep 17 00:00:00 2001
From: Ivan Maidanski <ivmai@mail.ru>
Date: Sat, 25 Oct 2025 23:19:33 +0300
Subject: [PATCH] Fix SIGSEGV in remove_all_threads_but_me if fork from
unregistered thread (a cherry-pick of commit 44fbb3b9e from 'master')
Issue #783 (bdwgc).
Some clients call `fork()` from an unregistered thread, thus we might
find no entry for the current thread in `GC_remove_all_threads_but_me`.
* include/gc.h (GC_atfork_child): Add comment about `fork()` from
an unregistered thread.
* pthread_support.c [CAN_HANDLE_FORK] (GC_remove_all_threads_but_me):
If `me` is null, then return immediately after loop (instead of `ABORT`
or the assertion, regardless of `CPPCHECK` and `LINT2`).
* win32_threads.c [CAN_HANDLE_FORK] (GC_remove_all_threads_but_me):
Likewise.
---
include/gc.h | 1 +
pthread_support.c | 19 ++++++++-----------
win32_threads.c | 4 +++-
3 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/include/gc.h b/include/gc.h
index 54d704a06..b929240fc 100644
--- a/include/gc.h
+++ b/include/gc.h
@@ -512,6 +512,7 @@ GC_API void GC_CALL GC_set_handle_fork(int);
/* non-zero); GC_atfork_child is to be called immediately in the child */
/* branch (i.e., fork result is 0). Note that GC_atfork_child() call */
/* should, of course, precede GC_start_mark_threads call (if any). */
+/* Note that fork() could be called from an unregistered thread. */
GC_API void GC_CALL GC_atfork_prepare(void);
GC_API void GC_CALL GC_atfork_parent(void);
GC_API void GC_CALL GC_atfork_child(void);
diff --git a/pthread_support.c b/pthread_support.c
index dbde77f25..0efbcdd9c 100644
--- a/pthread_support.c
+++ b/pthread_support.c
@@ -829,11 +829,11 @@ GC_API void GC_CALL GC_register_altstack(void *stack, GC_word stack_size,
GC_threads[hv] = me;
}
-/* Remove all entries from the GC_threads table, except the one for */
-/* the current thread. Also update thread identifiers stored in */
-/* the table for the current thread. We need to do this in the */
-/* child process after a fork(), since only the current thread */
-/* survives in the child. */
+/* Remove all entries from the GC_threads table, except the one (if */
+/* any) for the current thread. Also update thread identifiers */
+/* stored in the table for the current thread. We need to do this */
+/* in the child process after a fork(), since only the current */
+/* thread survives in the child. */
STATIC void GC_remove_all_threads_but_me(void)
{
int hv;
@@ -870,12 +870,9 @@ STATIC void GC_remove_all_threads_but_me(void)
store_to_threads_table(hv, NULL);
}
-# if defined(CPPCHECK) || defined(LINT2)
- if (NULL == me)
- ABORT("Current thread is not found after fork");
-# else
- GC_ASSERT(me != NULL);
-# endif
+ if (NULL == me)
+ return; /* fork() is called from an unregistered thread */
+
/* Update pthread's id as it is not guaranteed to be the same */
/* between this (child) process and the parent one. */
me -> id = pthread_self();
diff --git a/win32_threads.c b/win32_threads.c
index d1b7d5dbe..0335085ed 100644
--- a/win32_threads.c
+++ b/win32_threads.c
@@ -1185,8 +1185,10 @@ GC_API void * GC_CALL GC_get_my_stackbottom(struct GC_stack_base *sb)
GC_threads[hv] = NULL;
}
+ if (NULL == me)
+ return; /* fork() is called from an unregistered thread */
+
/* Put "me" back to GC_threads. */
- GC_ASSERT(me != NULL);
thread_id = GetCurrentThreadId(); /* differs from that in parent */
GC_threads[THREAD_TABLE_INDEX(thread_id)] = me;
From 1058994bc264dd99a7b6d3caefe0c129bfbd1fb7 Mon Sep 17 00:00:00 2001
From: Ivan Maidanski <ivmai@mail.ru>
Date: Thu, 30 Oct 2025 23:39:44 +0300
Subject: [PATCH] Fix code defect of LOCK/UNLOCK in separate 'if' in
GC_generic_malloc_many (a cherry-pick of commit c7d342c83 from 'master')
* mallocx.c [PARALLEL_MARK] (GC_generic_malloc_many): Check
`GC_parallel` once around `GC_reclaim_generic()` call (so that
nearby `UNLOCK()` and the following `LOCK()` to be placed inside
a single `if` statement block).
---
mallocx.c | 82 +++++++++++++++++++++++++++----------------------------
1 file changed, 41 insertions(+), 41 deletions(-)
diff --git a/mallocx.c b/mallocx.c
index 340bd5231..927008958 100644
--- a/mallocx.c
+++ b/mallocx.c
@@ -374,54 +374,54 @@ GC_API void GC_CALL GC_generic_malloc_many(size_t lb, int k, void **result)
++ GC_fl_builder_count;
UNLOCK();
GC_release_mark_lock();
- }
-# endif
- op = GC_reclaim_generic(hbp, hhdr, lb,
- ok -> ok_init, 0, &my_bytes_allocd);
- if (op != 0) {
-# ifdef PARALLEL_MARK
- if (GC_parallel) {
- *result = op;
- (void)AO_fetch_and_add(&GC_bytes_allocd_tmp,
- (AO_t)my_bytes_allocd);
+
+ op = GC_reclaim_generic(hbp, hhdr, lb, ok -> ok_init, NULL,
+ &my_bytes_allocd);
+ if (op != NULL) {
+ *result = op;
+ (void)AO_fetch_and_add(&GC_bytes_allocd_tmp,
+ (AO_t)my_bytes_allocd);
+ GC_acquire_mark_lock();
+ -- GC_fl_builder_count;
+ if (GC_fl_builder_count == 0) GC_notify_all_builder();
+# ifdef THREAD_SANITIZER
+ GC_release_mark_lock();
+ LOCK();
+ GC_bytes_found += my_bytes_allocd;
+ UNLOCK();
+# else
+ GC_bytes_found += my_bytes_allocd;
+ /* The result may be inaccurate. */
+ GC_release_mark_lock();
+# endif
+ (void) GC_clear_stack(0);
+ return;
+ }
+
GC_acquire_mark_lock();
-- GC_fl_builder_count;
if (GC_fl_builder_count == 0) GC_notify_all_builder();
-# ifdef THREAD_SANITIZER
- GC_release_mark_lock();
- LOCK();
- GC_bytes_found += my_bytes_allocd;
- UNLOCK();
-# else
- GC_bytes_found += my_bytes_allocd;
- /* The result may be inaccurate. */
- GC_release_mark_lock();
-# endif
- (void) GC_clear_stack(0);
- return;
- }
-# endif
- /* We also reclaimed memory, so we need to adjust */
- /* that count. */
+ GC_release_mark_lock();
+ LOCK();
+ /* GC lock is needed for reclaim list access. We */
+ /* must decrement fl_builder_count before reacquiring */
+ /* the lock. Hopefully this path is rare. */
+
+ rlh = ok -> ok_reclaim_list; /* reload rlh after locking */
+ if (NULL == rlh) break;
+ continue;
+ }
+# endif
+
+ op = GC_reclaim_generic(hbp, hhdr, lb, ok -> ok_init, NULL,
+ &my_bytes_allocd);
+ if (op != NULL) {
+ /* We also reclaimed memory, so we need to adjust */
+ /* that count. */
GC_bytes_found += my_bytes_allocd;
GC_bytes_allocd += my_bytes_allocd;
goto out;
}
-# ifdef PARALLEL_MARK
- if (GC_parallel) {
- GC_acquire_mark_lock();
- -- GC_fl_builder_count;
- if (GC_fl_builder_count == 0) GC_notify_all_builder();
- GC_release_mark_lock();
- LOCK();
- /* GC lock is needed for reclaim list access. We */
- /* must decrement fl_builder_count before reacquiring */
- /* the lock. Hopefully this path is rare. */
-
- rlh = ok -> ok_reclaim_list; /* reload rlh after locking */
- if (NULL == rlh) break;
- }
-# endif
}
}
/* Next try to use prefix of global free list if there is one. */
From 73fdfdaf45fd35993c7f9e051875147ca39438c4 Mon Sep 17 00:00:00 2001
From: Ivan Maidanski <ivmai@mail.ru>
Date: Fri, 31 Oct 2025 22:44:52 +0300
Subject: [PATCH] Fix SIGSEGV if pthread_detach is called before collector
initialization (a cherry-pick of commit e40697e26 from 'master')
The only case this seems to be needed is when the client calls
`pthread_detach(pthread_self())` before the collector initialization.
* pthread_support.c [!SN_TARGET_ORBIS && !SN_TARGET_PSP2]
(GC_pthread_detach): Call `GC_init()` if the collector is not
initialized; add comment.
* win32_threads.c [GC_PTHREADS] (GC_pthread_detach): Likewise.
---
pthread_support.c | 7 +++++++
win32_threads.c | 1 +
2 files changed, 8 insertions(+)
diff --git a/pthread_support.c b/pthread_support.c
index 0efbcdd9c..fb09f3d17 100644
--- a/pthread_support.c
+++ b/pthread_support.c
@@ -2016,6 +2016,13 @@ GC_INNER_PTHRSTART void GC_thread_exit_proc(void *arg)
DCL_LOCK_STATE;
INIT_REAL_SYMS();
+ if (!EXPECT(GC_is_initialized, TRUE)) {
+ /*
+ * The only case this seems to be needed is when the client calls
+ * pthread_detach(pthread_self()) before the collector initialization.
+ */
+ GC_init();
+ }
LOCK();
t = (GC_thread)COVERT_DATAFLOW(GC_lookup_thread(thread));
UNLOCK();
diff --git a/win32_threads.c b/win32_threads.c
index 0335085ed..0ec33cf95 100644
--- a/win32_threads.c
+++ b/win32_threads.c
@@ -3257,6 +3257,7 @@ GC_INNER void GC_thr_init(void)
GC_thread t;
DCL_LOCK_STATE;
+ if (!EXPECT(GC_is_initialized, TRUE)) GC_init();
GC_ASSERT(!GC_win32_dll_threads);
t = GC_lookup_pthread(thread);
result = pthread_detach(thread);
|
