lkml.org 
[lkml]   [2020]   [Jun]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] ovl: explicitly initialize error in ovl_copy_xattr()
On Wed, Jun 03, 2020 at 07:47:14PM +0200, glider@google.com wrote:
> Under certain circumstances (we found this out running Docker on a
> Clang-built kernel with CONFIG_INIT_STACK_ALL) ovl_copy_xattr() may
> return uninitialized value of |error| from ovl_copy_xattr().
> It is then returned by ovl_create() to lookup_open(), which casts it to
> an invalid dentry pointer, that can be further read or written by the
> lookup_open() callers.
>
> Signed-off-by: Alexander Potapenko <glider@google.com>

Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1050405
Fixes: e4ad29fa0d22 ("ovl: use a minimal buffer in ovl_copy_xattr")
Cc: stable@vger.kernel.org
Reviewed-by: Kees Cook <keescook@chromium.org>

It seems the error isn't reported anywhere, so the value likely isn't
too important. -EINVAL seems sane to me.

Thought: should CONFIG_INIT_STACK_ALL=y disable uninitialized_var()?

$ git grep uninitialized_var | wc -l
300

We have evidence this is being used inappropriately and is masking bugs.
I would actually think it should should be removed globally, but it
seems especially important for CONFIG_INIT_STACK_ALL=y.

I've opened:
https://github.com/KSPP/linux/issues/81

--
Kees Cook

\
 
 \ /
  Last update: 2020-06-03 22:36    [W:0.065 / U:0.976 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site