Re: [PATCH] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info()

Alexander Potapenko
2020-04-21T08:01:14Z

On Tue, Apr 21, 2020 at 12:33 AM Andrew Morton
<akpm@linux-foundation.org> wrote:
>
> On Sun, 19 Apr 2020 12:08:48 +0200 glider@google.com wrote:
>
> > KMSAN reported uninitialized data being written to disk when dumping
> > core. As a result, several kilobytes of kmalloc memory may be written to
> > the core file and then read by a non-privileged user.
> >
> > ...
> >
> > --- a/fs/binfmt_elf.c
> > +++ b/fs/binfmt_elf.c
> > @@ -1733,7 +1733,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
> > (!regset->active || regset->active(t->task, regset) > 0)) {
> > int ret;
> > size_t size = regset_size(t->task, regset);
> > - void *data = kmalloc(size, GFP_KERNEL);
> > + void *data = kzalloc(size, GFP_KERNEL);
> > if (unlikely(!data))
> > return 0;
> > ret = regset->get(t->task, regset,
>
> This seems to be a quite easy way of exposing quite a large amount of
> kernel memory contents, so I think I'll add a cc:stable to this patch?

Correct. Sorry, I forgot about this.

The reporter is also happy with the Reported-by: tag, so you can
ignore the note.

--
Alexander Potapenko
Software Engineer

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