linux-kernel - Re: [PATCH] android: binder: fix type mismatch warning

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Date:   Mon, 18 Sep 2017 16:02:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Arve Hjønnevåg <arve@...roid.com>,
        Riley Andrews <riandrews@...roid.com>,
        devel@...verdev.osuosl.org, Todd Kjos <tkjos@...roid.com>,
        linux-kernel@...r.kernel.org, John Stultz <john.stultz@...aro.org>,
        Martijn Coenen <maco@...roid.com>
Subject: Re: [PATCH] android: binder: fix type mismatch warning

On Tue, Sep 05, 2017 at 10:56:13AM +0200, Arnd Bergmann wrote:
> Allowing binder to expose the 64-bit API on 32-bit kernels caused a
> build warning:
> 
> drivers/android/binder.c: In function 'binder_transaction_buffer_release':
> drivers/android/binder.c:2220:15: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>     fd_array = (u32 *)(parent_buffer + fda->parent_offset);
>                ^
> drivers/android/binder.c: In function 'binder_translate_fd_array':
> drivers/android/binder.c:2445:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>   fd_array = (u32 *)(parent_buffer + fda->parent_offset);
>              ^
> drivers/android/binder.c: In function 'binder_fixup_parent':
> drivers/android/binder.c:2511:18: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> 
> This adds extra type casts to avoid the warning.
> 
> However, there is another problem with the Kconfig option: turning
> it on or off creates two incompatible ABI versions, a kernel that
> has this enabled cannot run user space that was built without it
> or vice versa. A better solution might be to leave the option hidden
> until the binder code is fixed to deal with both ABI versions.

I don't know if that is ever going to be fixed, as it's not an issue
that you will ever see "in the wild" from what I can tell...

thanks,

greg k-h