From: Michael Ellerman <mpe@ellerman.id.au>
To: Kees Cook <keescook@chromium.org>, Christoph Lameter <cl@linux.com>
Cc: "kernel-hardening\@lists.openwall.com"
<kernel-hardening@lists.openwall.com>, Jan Kara <jack@suse.cz>,
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<linux-arm-kernel@lists.infradead.org>
Subject: Re: [kernel-hardening] Re: [PATCH 9/9] mm: SLUB hardened usercopy support
Date: Sat, 09 Jul 2016 15:58:20 +1000 [thread overview]
Message-ID: <8737njpd37.fsf@@concordia.ellerman.id.au> (raw)
In-Reply-To: <CAGXu5jKxw3RxWNKLX4XVCwJ6x_zA=_RwiU9jLDm2+VRO79G7+w@mail.gmail.com>
Kees Cook <keescook@chromium.org> writes:
> On Fri, Jul 8, 2016 at 1:41 PM, Kees Cook <keescook@chromium.org> wrote:
>> So, as found already, the position in the usercopy check needs to be
>> bumped down by red_left_pad, which is what Michael's fix does, so I'll
>> include it in the next version.
>
> Actually, after some offline chats, I think this is better, since it
> makes sure the ptr doesn't end up somewhere weird before we start the
> calculations. This leaves the pointer as-is, but explicitly handles
> the redzone on the offset instead, with no wrapping, etc:
>
> /* Find offset within object. */
> offset = (ptr - page_address(page)) % s->size;
>
> + /* Adjust for redzone and reject if within the redzone. */
> + if (s->flags & SLAB_RED_ZONE) {
> + if (offset < s->red_left_pad)
> + return s->name;
> + offset -= s->red_left_pad;
> + }
> +
> /* Allow address range falling entirely within object size. */
> if (offset <= s->object_size && n <= s->object_size - offset)
> return NULL;
That fixes the case for me in kstrndup(), which allows the system to boot.
I then get two hits, which may or may not be valid:
[ 2.309556] usercopy: kernel memory overwrite attempt detected to d000000003510028 (kernfs_node_cache) (64 bytes)
[ 2.309995] CPU: 7 PID: 2241 Comm: wait-for-root Not tainted 4.7.0-rc3-00099-g97872fc89d41 #64
[ 2.310480] Call Trace:
[ 2.310556] [c0000001f4773bf0] [c0000000009bdbe8] dump_stack+0xb0/0xf0 (unreliable)
[ 2.311016] [c0000001f4773c30] [c00000000029cf44] __check_object_size+0x74/0x320
[ 2.311472] [c0000001f4773cb0] [c00000000005d4d0] copy_from_user+0x60/0xd4
[ 2.311873] [c0000001f4773cf0] [c0000000008b38f4] __get_filter+0x74/0x160
[ 2.312230] [c0000001f4773d30] [c0000000008b408c] sk_attach_filter+0x2c/0xc0
[ 2.312596] [c0000001f4773d60] [c000000000871c34] sock_setsockopt+0x954/0xc00
[ 2.313021] [c0000001f4773dd0] [c00000000086ac44] SyS_setsockopt+0x134/0x150
[ 2.313380] [c0000001f4773e30] [c000000000009260] system_call+0x38/0x108
[ 2.317045] usercopy: kernel memory overwrite attempt detected to d000000003530028 (kernfs_node_cache) (64 bytes)
[ 2.317297] CPU: 10 PID: 2242 Comm: wait-for-root Not tainted 4.7.0-rc3-00099-g97872fc89d41 #64
[ 2.317475] Call Trace:
[ 2.317511] [c0000001f471fbf0] [c0000000009bdbe8] dump_stack+0xb0/0xf0 (unreliable)
[ 2.317689] [c0000001f471fc30] [c00000000029cf44] __check_object_size+0x74/0x320
[ 2.317861] [c0000001f471fcb0] [c00000000005d4d0] copy_from_user+0x60/0xd4
[ 2.318011] [c0000001f471fcf0] [c0000000008b38f4] __get_filter+0x74/0x160
[ 2.318165] [c0000001f471fd30] [c0000000008b408c] sk_attach_filter+0x2c/0xc0
[ 2.318313] [c0000001f471fd60] [c000000000871c34] sock_setsockopt+0x954/0xc00
[ 2.318485] [c0000001f471fdd0] [c00000000086ac44] SyS_setsockopt+0x134/0x150
[ 2.318632] [c0000001f471fe30] [c000000000009260] system_call+0x38/0x108
With:
# zgrep SLUB /proc/config.gz
CONFIG_SLUB_DEBUG=y
CONFIG_SLUB=y
CONFIG_SLUB_CPU_PARTIAL=y
CONFIG_SLUB_DEBUG_ON=y
# CONFIG_SLUB_STATS is not set
cheers
next prev parent reply other threads:[~2016-07-09 5:58 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-06 22:25 [PATCH 0/9] mm: Hardened usercopy Kees Cook
2016-07-06 22:25 ` [PATCH 1/9] " Kees Cook
2016-07-07 5:37 ` Baruch Siach
2016-07-07 17:25 ` Kees Cook
2016-07-07 18:35 ` Baruch Siach
2016-07-07 7:42 ` Thomas Gleixner
2016-07-07 17:29 ` Kees Cook
2016-07-07 19:34 ` Thomas Gleixner
2016-07-07 8:01 ` Arnd Bergmann
2016-07-07 17:37 ` Kees Cook
2016-07-08 5:34 ` Michael Ellerman
2016-07-08 9:22 ` Arnd Bergmann
2016-07-07 16:19 ` Rik van Riel
2016-07-07 16:35 ` Rik van Riel
2016-07-07 17:41 ` Kees Cook
2016-07-06 22:25 ` [PATCH 2/9] x86/uaccess: Enable hardened usercopy Kees Cook
2016-07-06 22:25 ` [PATCH 3/9] ARM: uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 4/9] arm64/uaccess: " Kees Cook
2016-07-07 10:07 ` Mark Rutland
2016-07-07 17:19 ` Kees Cook
2016-07-06 22:25 ` [PATCH 5/9] ia64/uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 6/9] powerpc/uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 7/9] sparc/uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 8/9] mm: SLAB hardened usercopy support Kees Cook
2016-07-06 22:25 ` [PATCH 9/9] mm: SLUB " Kees Cook
2016-07-07 4:35 ` Michael Ellerman
[not found] ` <577ddc18.d351190a.1fa54.ffffbe79SMTPIN_ADDED_BROKEN@mx.google.com>
2016-07-07 18:56 ` [kernel-hardening] " Kees Cook
2016-07-08 10:19 ` Michael Ellerman
2016-07-08 13:45 ` Christoph Lameter
2016-07-08 16:07 ` Kees Cook
2016-07-08 16:20 ` Christoph Lameter
2016-07-08 17:41 ` Kees Cook
2016-07-08 20:48 ` Kees Cook
2016-07-09 5:58 ` Michael Ellerman [this message]
2016-07-09 6:07 ` Michael Ellerman
[not found] ` <57809299.84b3370a.5390c.ffff9e58SMTPIN_ADDED_BROKEN@mx.google.com>
2016-07-09 6:17 ` Valdis.Kletnieks
2016-07-09 17:07 ` Kees Cook
2016-07-11 6:08 ` Joonsoo Kim
2016-07-07 7:30 ` [PATCH 0/9] mm: Hardened usercopy Christian Borntraeger
2016-07-07 17:27 ` Kees Cook
2016-07-08 8:46 ` Ingo Molnar
2016-07-08 16:19 ` Linus Torvalds
2016-07-08 18:23 ` Ingo Molnar
2016-07-09 2:22 ` Laura Abbott
2016-07-09 2:44 ` Rik van Riel
2016-07-09 7:55 ` Ingo Molnar
2016-07-09 8:25 ` Ard Biesheuvel
2016-07-09 12:58 ` Laura Abbott
2016-07-09 17:03 ` Kees Cook
2016-07-09 17:01 ` Kees Cook
2016-07-09 21:27 ` Andy Lutomirski
2016-07-09 23:16 ` PaX Team
2016-07-10 9:16 ` Ingo Molnar
2016-07-10 12:03 ` PaX Team
2016-07-10 12:38 ` Andy Lutomirski
2016-07-11 18:40 ` Kees Cook
2016-07-11 18:34 ` Kees Cook
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