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Date:   Tue, 22 Oct 2019 05:30:51 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Ben Hutchings <ben.hutchings@codethink.co.uk>,
        y2038 Mailman List <y2038@lists.linaro.org>,
        Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [Y2038] [PATCH v6 10/43] compat_ioctl: move rtc handling into
 rtc-dev.c
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On Thu, Oct 17, 2019 at 04:33:09PM +0200, Arnd Bergmann wrote:

> However, looking at this again after your comment I found a rather
> more serious bug in my new RTC_IRQP_SET handling: Any 64-bit
> machine can now bypass the permission check for RTC_IRQP_SET by
> calling RTC_IRQP_SET32 instead.

You've lost the check on RTC_EPOCH_SET as well.

Another potential issue is drivers/input/misc/hp_sdc_rtc.c,
provided that the hardware in question might possibly exist
on hppa64 boxen - CONFIG_GSC defaults to y and it's not
32bit-only, so that thing is at least selectable on 64bit
kernels.