The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7aa135fcf26377f92dc0680a57566b4c7f3e281b Mon Sep 17 00:00:00 2001

From: Martijn Coenen maco@android.com Date: Wed, 28 Mar 2018 11:14:50 +0200 Subject: [PATCH] ANDROID: binder: prevent transactions into own process.

This can't happen with normal nodes (because you can't get a ref to a node you own), but it could happen with the context manager; to make the behavior consistent with regular nodes, reject transactions into the context manager by the process owning it.

Reported-by: syzbot+09e05aba06723a94d43d@syzkaller.appspotmail.com Signed-off-by: Martijn Coenen maco@android.com Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 764b63a5aade..e578eee31589 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2839,6 +2839,14 @@ static void binder_transaction(struct binder_proc *proc, else return_error = BR_DEAD_REPLY; mutex_unlock(&context->context_mgr_node_lock); + if (target_node && target_proc == proc) { + binder_user_error("%d:%d got transaction to context manager from process owning it\n", + proc->pid, thread->pid); + return_error = BR_FAILED_REPLY; + return_error_param = -EINVAL; + return_error_line = __LINE__; + goto err_invalid_target_handle; + } } if (!target_node) { /*