Staging: binder: Prevent the wrong thread from adding a transaction to the stack.

If a thread is part of a transaction stack, it is only allowed to make
another call if it was the target of the top transaction on the stack.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 91a96292e6bb..b0127a3290d0 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -1343,6 +1343,17 @@ binder_transaction(struct binder_proc *proc, struct binder_thread *thread,
                 if (!(tr->flags & TF_ONE_WAY) && thread->transaction_stack) {
                         struct binder_transaction *tmp;
                         tmp = thread->transaction_stack;
+                        if (tmp->to_thread != thread) {
+                                binder_user_error("binder: %d:%d got new "
+                                        "transaction with bad transaction stack"
+                                        ", transaction %d has target %d:%d\n",
+                                        proc->pid, thread->pid, tmp->debug_id,
+                                        tmp->to_proc ? tmp->to_proc->pid : 0,
+                                        tmp->to_thread ?
+                                        tmp->to_thread->pid : 0);
+                                return_error = BR_FAILED_REPLY;
+                                goto err_bad_call_stack;
+                        }
                         while (tmp) {
                                 if (tmp->from && tmp->from->proc == target_proc)
                                         target_thread = tmp->from;