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From: Randy Dunlap <>
To: "Russell King (Oracle)" <>
Cc: Steve French <>,
	CIFS <>,
	linux-fsdevel <>,
	LAK <>
Subject: Re: Fwd: [EXTERNAL] Re: ioctl.c:undefined reference to `__get_user_bad'
Date: Tue, 18 May 2021 18:48:04 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 5/18/21 3:03 AM, Russell King (Oracle) wrote:
> On Mon, May 17, 2021 at 02:06:33PM -0700, Randy Dunlap wrote:
>> [adding back linux-arm-kernel; what happened to it? ]

That was about what I thought was Steve F. dropping LAK on his response email.

> Nothing. I'm not interested in trying to do major disgusting
> contortions to make get_user() work for 8-byte values. If someone
> else wants to put the effort in and come up with an elegant solution
> that doesn't add warnings over the rest of the kernel, that's fine.
> As far as I remember, everything in __get_user_err() relies on
> __gu_val _not_ being 64-bit. If we use the same trick that we do
> in __get_user_check():
> 	__inttype(x) __gu_val = (x);
> then if get_user() is called with a 64-bit integer value and a
> pointer-to-32-bit location to fetch from, we'd end up passing a
> 64-bit integer into the __get_user_asm() which could access the
> wrong 32-bit half of the value in BE mode. Similar issue with
> 64-bit vs pointer-to-16-bit.

Yes, trying to handle get_user() of size 8 bytes is quite messy.
I have a few versions and they are all ugly and cause build warnings.

So we are down to what bugzilla calls WONTFIX. I'm OK with that.



  reply	other threads:[~2021-05-19  1:48 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
     [not found] ` <>
     [not found]   ` <>
2021-05-17 17:13     ` Fwd: [EXTERNAL] Re: ioctl.c:undefined reference to `__get_user_bad' Steve French
2021-05-17 21:04       ` Randy Dunlap
2021-05-17 21:06         ` Randy Dunlap
2021-05-18 10:03           ` Russell King (Oracle)
2021-05-19  1:48             ` Randy Dunlap [this message]
2021-05-19  9:11         ` Aurélien Aptel

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