Messages in this thread | | | Date | Fri, 25 Apr 2014 21:05:32 +0200 | From | Mateusz Guzik <> | Subject | Re: Clarification needed on use of put_user inside a loop |
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On Fri, Apr 25, 2014 at 09:39:57PM +0530, Kumar Gaurav wrote: > Hence when transferring data involves loops then checking permission > (using access_ok()) once should be good to go then after we can > simply transfer data using __put_user(), instead of using put_user() > itself in loop. >
Well, I can't tell you whether this is a good idea, but:
This looks correct and other code is doing this already.
However, put_user calls might_fault, but __put_user consumers I found (e.g. copy_siginfo_to_user) don't do that.
While it has only debugging purposes and would not change anything for those consumers, it seems to be a bug to not include it.
Thus I suggest adding access_ok variant which calls might_fault.
-- Mateusz Guzik
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