From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: glider@google.com, adobriyan@gmail.com,
linux-kernel@vger.kernel.org, sunhaoyl@outlook.com,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info()
Date: Wed, 27 May 2020 14:55:15 -0700 [thread overview]
Message-ID: <202005271450.7468AA95@keescook> (raw)
In-Reply-To: <202004201540.01C8F82B@keescook>
On Mon, Apr 20, 2020 at 03:41:40PM -0700, Kees Cook wrote:
> On Mon, Apr 20, 2020 at 03:33:52PM -0700, Andrew Morton 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.
>
> Ewww. That's been there for 12 years. Did something change in
> regset_size() or regset->get()? Do you know what leaves the hole?
>
> > >
> > > ...
> > >
> > > --- 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?
>
> Yes please.
>
> Acked-by: Kees Cook <keescook@chromium.org>
This has been in -next for a while, but we need to get this landed and
into -stable. Can you please send this to Linus for the final release? I
know Al is working on getting the complementary fixes landed too, but
this fix is also sufficient, trivial to backport, and provides some
future-proofing/defense in depth.
-Kees
--
Kees Cook
next prev parent reply other threads:[~2020-05-27 21:55 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-19 10:08 [PATCH] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info() glider
2020-04-19 10:10 ` Alexander Potapenko
2020-04-20 22:33 ` Andrew Morton
2020-04-20 22:41 ` Kees Cook
2020-04-21 3:42 ` Al Viro
2020-04-21 8:14 ` Alexander Potapenko
2020-05-12 1:09 ` Al Viro
2020-05-12 3:44 ` Al Viro
2020-05-12 8:20 ` Alexander Potapenko
2020-05-13 3:33 ` Al Viro
2020-05-24 23:45 ` Al Viro
2020-05-26 22:38 ` Al Viro
2020-05-27 12:08 ` Alexander Potapenko
2020-05-27 19:04 ` Borislav Petkov
2020-05-27 19:53 ` Al Viro
2020-05-27 20:09 ` Borislav Petkov
2020-04-21 12:54 ` Alexander Potapenko
2020-04-21 15:09 ` Jann Horn
2020-04-21 16:04 ` Yu-cheng Yu
2020-04-21 16:16 ` Jann Horn
2020-04-21 16:26 ` Yu-cheng Yu
2020-04-21 20:20 ` Kees Cook
2020-04-21 8:06 ` Alexander Potapenko
2020-05-27 21:55 ` Kees Cook [this message]
2020-04-21 8:00 ` Alexander Potapenko
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