--- zzzz-none-000/linux-4.4.271/drivers/android/binder.c	2021-06-03 06:22:09.000000000 +0000
+++ maple-fsgw-759/linux-4.4.271/drivers/android/binder.c	2023-12-20 10:37:05.000000000 +0000
@@ -303,6 +303,7 @@
 	struct mm_struct *vma_vm_mm;
 	struct task_struct *tsk;
 	struct files_struct *files;
+	struct mutex files_lock;
 	struct hlist_node deferred_work_node;
 	int deferred_work;
 	void *buffer;
@@ -377,20 +378,26 @@
 
 static int task_get_unused_fd_flags(struct binder_proc *proc, int flags)
 {
-	struct files_struct *files = proc->files;
 	unsigned long rlim_cur;
 	unsigned long irqs;
+	int ret;
 
-	if (files == NULL)
-		return -ESRCH;
-
-	if (!lock_task_sighand(proc->tsk, &irqs))
-		return -EMFILE;
-
+	mutex_lock(&proc->files_lock);
+	if (proc->files == NULL) {
+		ret = -ESRCH;
+		goto err;
+	}
+	if (!lock_task_sighand(proc->tsk, &irqs)) {
+		ret = -EMFILE;
+		goto err;
+	}
 	rlim_cur = task_rlimit(proc->tsk, RLIMIT_NOFILE);
 	unlock_task_sighand(proc->tsk, &irqs);
 
-	return __alloc_fd(files, 0, rlim_cur, flags);
+	ret = __alloc_fd(proc->files, 0, rlim_cur, flags);
+err:
+	mutex_unlock(&proc->files_lock);
+	return ret;
 }
 
 /*
@@ -399,8 +406,10 @@
 static void task_fd_install(
 	struct binder_proc *proc, unsigned int fd, struct file *file)
 {
+	mutex_lock(&proc->files_lock);
 	if (proc->files)
 		__fd_install(proc->files, fd, file);
+	mutex_unlock(&proc->files_lock);
 }
 
 /*
@@ -410,9 +419,11 @@
 {
 	int retval;
 
-	if (proc->files == NULL)
-		return -ESRCH;
-
+	mutex_lock(&proc->files_lock);
+	if (proc->files == NULL) {
+		retval = -ESRCH;
+		goto err;
+	}
 	retval = __close_fd(proc->files, fd);
 	/* can't restart close syscall because file table entry was cleared */
 	if (unlikely(retval == -ERESTARTSYS ||
@@ -420,7 +431,8 @@
 		     retval == -ERESTARTNOHAND ||
 		     retval == -ERESTART_RESTARTBLOCK))
 		retval = -EINTR;
-
+err:
+	mutex_unlock(&proc->files_lock);
 	return retval;
 }
 
@@ -2979,7 +2991,9 @@
 	binder_insert_free_buffer(proc, buffer);
 	proc->free_async_space = proc->buffer_size / 2;
 	barrier();
+	mutex_lock(&proc->files_lock);
 	proc->files = get_files_struct(current);
+	mutex_unlock(&proc->files_lock);
 	proc->vma = vma;
 	proc->vma_vm_mm = vma->vm_mm;
 
@@ -3015,6 +3029,7 @@
 		return -ENOMEM;
 	get_task_struct(current->group_leader);
 	proc->tsk = current->group_leader;
+	mutex_init(&proc->files_lock);
 	INIT_LIST_HEAD(&proc->todo);
 	init_waitqueue_head(&proc->wait);
 	proc->default_priority = task_nice(current);
@@ -3253,9 +3268,11 @@
 
 		files = NULL;
 		if (defer & BINDER_DEFERRED_PUT_FILES) {
+			mutex_lock(&proc->files_lock);
 			files = proc->files;
 			if (files)
 				proc->files = NULL;
+			mutex_unlock(&proc->files_lock);
 		}
 
 		if (defer & BINDER_DEFERRED_FLUSH)
@@ -3657,13 +3674,24 @@
 
 static int binder_proc_show(struct seq_file *m, void *unused)
 {
+	struct binder_proc *itr;
 	struct binder_proc *proc = m->private;
 	int do_lock = !binder_debug_no_lock;
+	bool valid_proc = false;
 
 	if (do_lock)
 		binder_lock(__func__);
-	seq_puts(m, "binder proc state:\n");
-	print_binder_proc(m, proc, 1);
+
+	hlist_for_each_entry(itr, &binder_procs, proc_node) {
+		if (itr == proc) {
+			valid_proc = true;
+			break;
+		}
+	}
+	if (valid_proc) {
+		seq_puts(m, "binder proc state:\n");
+		print_binder_proc(m, proc, 1);
+	}
 	if (do_lock)
 		binder_unlock(__func__);
 	return 0;