Messages in this thread | | | Date | Mon, 5 May 2014 09:45:19 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: [PATCH] arm: put_user: fix possible data corruption in put_user |
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On Mon, 5 May 2014, Andrey Ryabinin wrote:
> On 05/05/14 13:01, Russell King - ARM Linux wrote: > > On Mon, May 05, 2014 at 10:13:58AM +0400, Andrey Ryabinin wrote: > >> According to arm procedure call standart r2 register is call-cloberred. > >> So after the result of x expression was put into r2 any following > >> function call in p may overwrite r2. To fix this, the result of p > >> expression must be saved to the temporary variable before the > >> assigment x expression to __r2. > > > > This and the patch make no sense. You talk about r2, but you're doing > > nothing with r2 in the patch. > > > > No, you didn't get it. I'll try to explain better. > > Lets consider following example: [...]
Thanks for the test code. I do confirm there is indeed a problem.
I'm trying to make sure your patch is actually the best fix.
Nicolas
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