On Wed, Nov 29, 2017 at 02:56:03PM -0800, Andrew Morton wrote: > On Mon, 27 Nov 2017 21:29:25 -0800 Andrei Vagin <ava...@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 ;)
It was a bug in criu. And this bug is on a minor path, which works when memfd_create() isn't available. It is a reason why I ask to not backport this patch to stable kernels. In CRIU this bug can be triggered, only if this patch will be backported to a kernel which version is lower than v3.16. > > Now I'm worried that it will break other things. I think a chance is very small. All programs should use names which listed in /proc/PID/map_files/.