linux-kernel - Re: [PATCH] binder: Remove bogus warning on failed same-process transaction

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Date:   Fri, 7 Aug 2020 16:06:21 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Jann Horn <jannh@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arve Hjønnevåg <arve@...roid.com>,
        Todd Kjos <tkjos@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Christian Brauner <christian@...uner.io>,
        Hridya Valsaraju <hridya@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] binder: Remove bogus warning on failed same-process
 transaction

On Thu, Aug 06, 2020 at 06:53:59PM +0200, Jann Horn wrote:
> While binder transactions with the same binder_proc as sender and recipient
> are forbidden, transactions with the same task_struct as sender and
> recipient are possible (even though currently there is a weird check in
> binder_transaction() that rejects them in the target==0 case).
> Therefore, task_struct identities can't be used to distinguish whether
> the caller is running in the context of the sender or the recipient.
> 
> Since I see no easy way to make this WARN_ON() useful and correct, let's
> just remove it.
> 
> Fixes: 44d8047f1d87 ("binder: use standard functions to allocate fds")
> Reported-by: syzbot+e113a0b970b7b3f394ba@...kaller.appspotmail.com
> Signed-off-by: Jann Horn <jannh@...gle.com>
> ---

Acked-by: Christian Brauner <christian.brauner@...ntu.com>

Thanks!
Christian