linux-kernel - Re: [ 044/218] Staging: Android alarm: IOCTL command encoding fix

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Message-ID: <CAMbhsRRP5ui-10hMEFYk2Rh93XrvKeircsZXsySE7YXF92qigQ@mail.gmail.com>
Date:	Sat, 3 Nov 2012 00:33:07 -0700
From:	Colin Cross <ccross@...gle.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	alan@...rguk.ukuu.org.uk, "Dae S. Kim" <dae@...atum.com>
Subject: Re: [ 044/218] Staging: Android alarm: IOCTL command encoding fix

On Fri, Sep 28, 2012 at 1:14 PM, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
> 3.4-stable review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
> From: "Dae S. Kim" <dae@...atum.com>
>
> commit 6bd4a5d96c08dc2380f8053b1bd4f879f55cd3c9 upstream.
>
> Fixed a bug. Data was being written to user space using an IOCTL
> command encoded with _IOC_WRITE access mode.
>
> Signed-off-by: Dae S. Kim <dae@...atum.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>
> ---
>  drivers/staging/android/android_alarm.h |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> --- a/drivers/staging/android/android_alarm.h
> +++ b/drivers/staging/android/android_alarm.h
> @@ -110,10 +110,12 @@ enum android_alarm_return_flags {
>  #define ANDROID_ALARM_WAIT                  _IO('a', 1)
>
>  #define ALARM_IOW(c, type, size)            _IOW('a', (c) | ((type) << 4), size)
> +#define ALARM_IOR(c, type, size)            _IOR('a', (c) | ((type) << 4), size)
> +
>  /* Set alarm */
>  #define ANDROID_ALARM_SET(type)             ALARM_IOW(2, type, struct timespec)
>  #define ANDROID_ALARM_SET_AND_WAIT(type)    ALARM_IOW(3, type, struct timespec)
> -#define ANDROID_ALARM_GET_TIME(type)        ALARM_IOW(4, type, struct timespec)
> +#define ANDROID_ALARM_GET_TIME(type)        ALARM_IOR(4, type, struct timespec)
>  #define ANDROID_ALARM_SET_RTC               _IOW('a', 5, struct timespec)
>  #define ANDROID_ALARM_BASE_CMD(cmd)         (cmd & ~(_IOC(0, 0, 0xf0, 0)))
>  #define ANDROID_ALARM_IOCTL_TO_TYPE(cmd)    (_IOC_NR(cmd) >> 4)
>
>
> --
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This patch breaks Android userspace by changing the ioctl ABI to
/dev/alarm.  It's definitely not a bug fix, as the IOW vs. IOR flag is
only ever used by drivers, and is not used by alarm-dev.c.

I would have commented sooner, but the original patch was not sent to
any lists I am on, nor any lists that Google can find.
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