linux-kernel - Re: [PATCH] binder: don't detect sender/target during buffer cleanup

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Message-ID: <20211102132336.GG2794@kadam>
Date:   Tue, 2 Nov 2021 16:23:36 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Todd Kjos <tkjos@...gle.com>
Cc:     gregkh@...uxfoundation.org, christian@...uner.io, arve@...roid.com,
        jannh@...gle.com, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, maco@...gle.com,
        joel@...lfernandes.org, kernel-team@...roid.com
Subject: Re: [PATCH] binder: don't detect sender/target during buffer cleanup

On Fri, Oct 15, 2021 at 04:38:11PM -0700, Todd Kjos wrote:
> When freeing txn buffers, binder_transaction_buffer_release()
> attempts to detect whether the current context is the target by
> comparing current->group_leader to proc->tsk. This is an unreliable
> test. Instead explicitly pass an 'is_failure' boolean.
> 
> Detecting the sender was being used as a way to tell if the
> transaction failed to be sent.  When cleaning up after
> failing to send a transaction, there is no need to close
> the fds associated with a BINDER_TYPE_FDA object. Now
> 'is_failure' can be used to accurately detect this case.
> 

It's really hard for me to understand what this bug looks like to the
user?  Is it a memory leak or do we free the wrong thing?

regards,
dan carpenter