Re: proc: fix /proc/*/map_files lookup

Andrew Morton
2017-11-29T22:56:06Z

On Mon, 27 Nov 2017 21:29:25 -0800 Andrei Vagin <avagin@virtuozzo.com> wrote:

> On Tue, Nov 21, 2017 at 12:27:06AM +0300, Alexey Dobriyan wrote:
> > Current code does:
> >
> > if (sscanf(dentry->d_name.name, "%lx-%lx", start, end) != 2)
> >
> > However sscanf() is broken garbage.
> >
> > It silently accepts whitespace between format specifiers
> > (did you know that?).
> >
> > It silently accepts valid strings which result in integer overflow.
> >
> > Do not use sscanf() for any even remotely reliable parsing code.
>
> This patch breaks criu, criu has one places where a file name is generated
> as map_files/%p-%p
>
> openat(1048572, "map_files/0x7f9912dd5000-0x7f9912de4000", O_RDWR) = -1 ENOENT (No such file or directory) <0.000015>
>
> And this code worked before this patch and it doesn't work with this
> patch. And you have to know that we never break user-space programs ;)
>
> But seriously, the patch looks good to me, but I would prefer to not queue
> it into stable kernels.

The patch breaks CRIU but you're OK with merging it? How does that work ;)

Now I'm worried that it will break other things.