From: Sam Ravnborg <sam@ravnborg.org>
To: "Shi, Yang" <yang.shi@linaro.org>
Cc: davem@davemloft.net, linux-kernel@vger.kernel.org,
sparclinux@vger.kernel.org, linaro-kernel@lists.linaro.org
Subject: Re: [V2 PATCH] sparc64/gup: check address scope legitimacy
Date: Sat, 05 Dec 2015 09:59:56 +0000 [thread overview]
Message-ID: <20151205095956.GA21826@ravnborg.org> (raw)
In-Reply-To: <5660C0D4.8050800@linaro.org>
> >access_ok() always returns 1.
>
> Thanks for pointing it out. And, I didn't notice that gup is just built for
> SPARC64. I though it is built by both 64 bit and 32 bit.
>
> A follow-up question, is there any reason to just have sparc specific fast
> gup for 64 bit not for 32 bit?
I do not know - sorry.
> >>@@ -203,6 +206,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
> >> addr = start;
> >> len = (unsigned long) nr_pages << PAGE_SHIFT;
> >> end = start + len;
> >>+ if (end < start)
> >>+ goto slow_irqon;
> >
> >end can only be smaller than start if there is some overflow.
> >See how end is calculated just the line above.
> >
> >This looks like a highly suspicious change.
>
> I'm supposed this is used to protect the overflow. I copied the code from
> other arch. Actually, every arch has this except sparc.
The the other archs are likely confused as well - there is most
likely some history behind that can be found if digging a little.
The code is not present in the generic version.
Sam
WARNING: multiple messages have this Message-ID (diff)
From: Sam Ravnborg <sam@ravnborg.org>
To: "Shi, Yang" <yang.shi@linaro.org>
Cc: davem@davemloft.net, linux-kernel@vger.kernel.org,
sparclinux@vger.kernel.org, linaro-kernel@lists.linaro.org
Subject: Re: [V2 PATCH] sparc64/gup: check address scope legitimacy
Date: Sat, 5 Dec 2015 10:59:56 +0100 [thread overview]
Message-ID: <20151205095956.GA21826@ravnborg.org> (raw)
In-Reply-To: <5660C0D4.8050800@linaro.org>
> >access_ok() always returns 1.
>
> Thanks for pointing it out. And, I didn't notice that gup is just built for
> SPARC64. I though it is built by both 64 bit and 32 bit.
>
> A follow-up question, is there any reason to just have sparc specific fast
> gup for 64 bit not for 32 bit?
I do not know - sorry.
> >>@@ -203,6 +206,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
> >> addr = start;
> >> len = (unsigned long) nr_pages << PAGE_SHIFT;
> >> end = start + len;
> >>+ if (end < start)
> >>+ goto slow_irqon;
> >
> >end can only be smaller than start if there is some overflow.
> >See how end is calculated just the line above.
> >
> >This looks like a highly suspicious change.
>
> I'm supposed this is used to protect the overflow. I copied the code from
> other arch. Actually, every arch has this except sparc.
The the other archs are likely confused as well - there is most
likely some history behind that can be found if digging a little.
The code is not present in the generic version.
Sam
next prev parent reply other threads:[~2015-12-05 9:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-25 22:31 [PATCH] sparc64/gup: check address scope legitimacy Yang Shi
2015-11-25 22:31 ` Yang Shi
2015-11-25 22:45 ` [V2 PATCH] " Yang Shi
2015-11-25 22:45 ` Yang Shi
2015-12-03 20:38 ` Sam Ravnborg
2015-12-03 20:38 ` Sam Ravnborg
2015-12-03 22:23 ` Shi, Yang
2015-12-03 22:23 ` Shi, Yang
2015-12-05 9:59 ` Sam Ravnborg [this message]
2015-12-05 9:59 ` Sam Ravnborg
2015-11-26 0:26 ` [PATCH] " kbuild test robot
2015-11-26 0:26 ` kbuild test robot
2015-11-26 0:31 ` Shi, Yang
2015-11-26 0:31 ` Shi, Yang
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