On Sun, Oct 17, 2010 at 19:36 +0200, Dan Carpenter wrote:
> On Sun, Oct 17, 2010 at 07:38:39PM +0400, Vasiliy Kulikov wrote:
> > On Sun, Oct 17, 2010 at 17:34 +0200, Jiri Slaby wrote:
> > > On 10/17/2010 04:41 PM, Vasiliy Kulikov wrote:
> > > > Structure new_line is copied to userland with some padding fields unitialized.
> > > > It leads to leaking of stack memory.
> > >
> > > I think your tool has a bug. I must admit I fail to see the padding
> > > which would cause leaks. Could you elaborate?
> >
> > I didn't use any tool except "grep copy_to_user" :)
> >
>
> It seems like you should be able to use pahole to make a list of
> structs with padding and then a checker script to find places where
> information is leaked.
Not all of these patches fix only padding zeroing, some of them fix
uninitialized fields. One struct has partly initialized array.
> Also someone complained to me about when I added a memset() in a fast
> path.
All these cases are ioctl() handlers or similar. I don't think ioctl()
should be so fast to become significantly slower with single memset().
> The thought was that it might be faster to just initialize it
> instead like:
>
> struct foo bar = {};
>
> In my case just using the initializer made the code cleaner so I did it,
> but neither of us actually benchmarked it.
>
> regards,
> dan carpenter
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Thanks,
--
Vasiliy
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