From: Dan Williams <dan.j.williams@intel.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arch@vger.kernel.org, Alan Cox <alan@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Netdev <netdev@vger.kernel.org>,
Greg KH <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Elena Reshetova <elena.reshetova@intel.com>,
"Linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
Subject: Re: [PATCH 07/18] [media] uvcvideo: prevent bounds-check bypass via speculative execution
Date: Mon, 8 Jan 2018 18:11:17 -0800 [thread overview]
Message-ID: <CAPcyv4jn3O-qLKMgpTj0M+U98rO6M09p2XCxQggVVtWnAGBnYQ@mail.gmail.com> (raw)
In-Reply-To: <8223870.kpF3YQejF4@avalon>
On Mon, Jan 8, 2018 at 3:23 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Dan,
>
> Thank you for the patch.
>
> On Saturday, 6 January 2018 03:10:32 EET Dan Williams wrote:
>> Static analysis reports that 'index' may be a user controlled value that
>> is used as a data dependency to read 'pin' from the
>> 'selector->baSourceID' array. In order to avoid potential leaks of
>> kernel memory values, block speculative execution of the instruction
>> stream that could issue reads based on an invalid value of 'pin'.
>
> I won't repeat the arguments already made in the thread regarding having
> documented coverity rules for this, even if I agree with them.
>
>> Based on an original patch by Elena Reshetova.
>>
>> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
>> Cc: linux-media@vger.kernel.org
>> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>> ---
>> drivers/media/usb/uvc/uvc_v4l2.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c
>> b/drivers/media/usb/uvc/uvc_v4l2.c index 3e7e283a44a8..7442626dc20e 100644
>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
>> @@ -22,6 +22,7 @@
>> #include <linux/mm.h>
>> #include <linux/wait.h>
>> #include <linux/atomic.h>
>> +#include <linux/compiler.h>
>>
>> #include <media/v4l2-common.h>
>> #include <media/v4l2-ctrls.h>
>> @@ -810,6 +811,7 @@ static int uvc_ioctl_enum_input(struct file *file, void
>> *fh, struct uvc_entity *iterm = NULL;
>> u32 index = input->index;
>> int pin = 0;
>> + __u8 *elem;
>>
>> if (selector == NULL ||
>> (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
>> @@ -820,8 +822,9 @@ static int uvc_ioctl_enum_input(struct file *file, void
>> *fh, break;
>> }
>> pin = iterm->id;
>> - } else if (index < selector->bNrInPins) {
>> - pin = selector->baSourceID[index];
>> + } else if ((elem = nospec_array_ptr(selector->baSourceID, index,
>> + selector->bNrInPins))) {
>> + pin = *elem;
>> list_for_each_entry(iterm, &chain->entities, chain) {
>> if (!UVC_ENTITY_IS_ITERM(iterm))
>> continue;
>
> (adding a bit more context)
>
>> if (iterm->id == pin)
>> break;
>> }
>> }
>>
>> if (iterm == NULL || iterm->id != pin)
>> return -EINVAL;
>>
>> memset(input, 0, sizeof(*input));
>> input->index = index;
>> strlcpy(input->name, iterm->name, sizeof(input->name));
>> if (UVC_ENTITY_TYPE(iterm) == UVC_ITT_CAMERA)
>> input->type = V4L2_INPUT_TYPE_CAMERA;
>
> So pin is used to search for an entry in the chain->entities list. Entries in
> that list are allocated separately through kmalloc and can thus end up in
> different cache lines, so I agree we have an issue. However, this is mitigated
> by the fact that typical UVC devices have a handful (sometimes up to a dozen)
> entities, so an attacker would only be able to read memory values that are
> equal to the entity IDs used by the device. Entity IDs can be freely allocated
> but typically count continuously from 0. It would take a specially-crafted UVC
> device to be able to read all memory.
>
> On the other hand, as this is nowhere close to being a fast path, I think we
> can close this potential hole as proposed in the patch. So,
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Thanks Laurent!
> Will you merge the whole series in one go, or would you like me to take the
> patch in my tree ? In the latter case I'll wait until the nospec_array_ptr()
> gets merged in mainline.
I'll track it for now. Until the 'nospec_array_ptr()' discussion
resolves there won't be a stabilized commit-id for you to base a
branch.
next prev parent reply other threads:[~2018-01-09 2:11 UTC|newest]
Thread overview: 161+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-06 1:09 [PATCH 00/18] prevent bounds-check bypass via speculative execution Dan Williams
2018-01-06 1:09 ` [PATCH 01/18] asm-generic/barrier: add generic nospec helpers Dan Williams
2018-01-06 2:55 ` Linus Torvalds
2018-01-06 5:23 ` Dan Williams
2018-01-06 17:08 ` Mark Rutland
2018-01-06 1:10 ` [PATCH 02/18] Documentation: document " Dan Williams
2018-01-08 16:29 ` Jonathan Corbet
2018-01-08 17:09 ` Mark Rutland
2018-01-08 21:19 ` Jonathan Corbet
2018-01-06 1:10 ` [PATCH 03/18] arm64: implement nospec_ptr() Dan Williams
2018-01-06 1:10 ` [PATCH 04/18] arm: " Dan Williams
2018-01-10 2:04 ` Laura Abbott
2018-01-10 7:40 ` Hanjun Guo
2018-01-10 17:24 ` Laura Abbott
2018-01-06 1:10 ` [PATCH 05/18] x86: implement nospec_barrier() Dan Williams
2018-01-06 1:10 ` [PATCH 06/18] x86, barrier: stop speculation for failed access_ok Dan Williams
2018-01-06 2:52 ` Linus Torvalds
2018-01-06 3:09 ` Linus Torvalds
2018-01-06 23:31 ` Dan Williams
2018-01-07 1:20 ` Linus Torvalds
2018-01-08 21:09 ` Dan Williams
2018-01-08 23:44 ` Linus Torvalds
2018-01-08 23:53 ` Dan Williams
2018-01-06 5:47 ` Dan Williams
2018-01-06 12:32 ` Alan Cox
2018-01-06 17:56 ` Linus Torvalds
2018-01-06 18:13 ` Alexei Starovoitov
2018-01-06 18:29 ` Dan Williams
2018-01-06 18:39 ` Alexei Starovoitov
2018-01-06 18:54 ` Dan Williams
2018-01-06 19:25 ` Alexei Starovoitov
2018-01-06 19:36 ` Dan Williams
2018-01-06 19:41 ` Thomas Gleixner
2018-01-08 10:02 ` Andrea Arcangeli
2018-01-06 18:38 ` Alan Cox
2018-01-06 18:51 ` Alexei Starovoitov
2018-01-06 19:55 ` Alan Cox
2018-01-06 20:09 ` Alexei Starovoitov
2018-01-06 20:22 ` Alan Cox
2018-01-06 21:17 ` Alexei Starovoitov
2018-01-06 21:21 ` Thomas Gleixner
2018-01-06 23:05 ` Alan Cox
2018-01-07 3:38 ` Alexei Starovoitov
2018-01-07 6:33 ` Willy Tarreau
2018-01-07 19:47 ` Linus Torvalds
2018-01-07 20:12 ` Willy Tarreau
2018-01-07 20:17 ` Linus Torvalds
2018-01-07 20:56 ` Thomas Gleixner
2018-01-08 2:23 ` David Miller
2018-01-08 7:38 ` Greg KH
2018-01-07 22:15 ` Willy Tarreau
2018-01-07 20:15 ` Dan Williams
2018-01-08 2:24 ` Alexei Starovoitov
2018-01-08 9:51 ` Peter Zijlstra
2018-01-08 18:21 ` Ingo Molnar
2018-01-08 12:00 ` David Laight
2018-01-08 12:12 ` Alan Cox
2018-01-08 12:33 ` David Laight
2018-01-07 10:08 ` Thomas Gleixner
2018-01-08 2:09 ` Alexei Starovoitov
2018-01-07 13:59 ` Alan Cox
2018-01-08 2:57 ` Alexei Starovoitov
2018-01-08 9:57 ` Peter Zijlstra
2018-01-06 20:42 ` Willy Tarreau
2018-01-07 1:36 ` David Miller
2018-01-07 17:19 ` James Bottomley
2018-01-07 18:31 ` Thomas Gleixner
2018-01-08 2:04 ` David Miller
2018-01-07 19:24 ` Alan Cox
2018-01-09 21:41 ` Josh Poimboeuf
2018-01-09 21:47 ` Dan Williams
2018-01-09 21:49 ` Josh Poimboeuf
2018-01-09 21:59 ` Dan Williams
2018-01-09 22:23 ` Josh Poimboeuf
2018-01-09 22:35 ` Dan Williams
2018-01-06 1:10 ` [PATCH 07/18] [media] uvcvideo: prevent bounds-check bypass via speculative execution Dan Williams
2018-01-06 9:09 ` Greg KH
2018-01-06 9:40 ` Greg KH
2018-01-06 17:41 ` Dan Williams
2018-01-07 9:09 ` Greg KH
2018-01-07 19:37 ` Dan Williams
2018-01-09 8:40 ` Laurent Pinchart
2018-01-09 10:04 ` Greg KH
2018-01-09 14:26 ` Laurent Pinchart
2018-01-09 14:47 ` Greg KH
2018-01-08 11:23 ` Laurent Pinchart
2018-01-09 2:11 ` Dan Williams [this message]
2018-01-06 1:10 ` [PATCH 08/18] carl9170: " Dan Williams
2018-01-06 10:01 ` Sergei Shtylyov
2018-01-06 14:23 ` Christian Lamparter
2018-01-06 15:06 ` Alan Cox
2018-01-06 16:38 ` Christian Lamparter
2018-01-06 16:34 ` Dan Williams
2018-01-06 1:10 ` [PATCH 09/18] p54: " Dan Williams
2018-01-06 10:01 ` Sergei Shtylyov
2018-01-06 1:10 ` [PATCH 10/18] qla2xxx: " Dan Williams
2018-01-06 9:03 ` Greg KH
2018-01-06 9:42 ` Greg KH
2018-01-11 22:15 ` Dan Williams
2018-01-12 7:27 ` Greg KH
2018-01-12 15:25 ` James Bottomley
2018-01-06 1:10 ` [PATCH 11/18] cw1200: " Dan Williams
2018-01-06 1:10 ` [PATCH 12/18] Thermal/int340x: " Dan Williams
2018-01-06 1:53 ` Srinivas Pandruvada
2018-01-06 1:57 ` Dan Williams
2018-01-06 17:24 ` Srinivas Pandruvada
2018-01-06 10:03 ` Sergei Shtylyov
2018-01-06 1:11 ` [PATCH 13/18] ipv6: " Dan Williams
2018-01-06 10:04 ` Sergei Shtylyov
2018-01-06 14:48 ` Stephen Hemminger
2018-01-06 18:05 ` Dan Williams
2018-01-06 1:11 ` [PATCH 14/18] ipv4: " Dan Williams
2018-01-06 9:00 ` Greg KH
2018-01-06 9:01 ` Greg KH
2018-01-06 12:23 ` Alan Cox
2018-01-06 15:14 ` Greg KH
2018-01-06 16:29 ` Dan Williams
2018-01-06 18:10 ` Dan Williams
2018-01-06 10:04 ` Sergei Shtylyov
2018-01-06 1:11 ` [PATCH 15/18] vfs, fdtable: " Dan Williams
2018-01-06 10:05 ` Sergei Shtylyov
2018-01-06 1:11 ` [PATCH 16/18] net: mpls: " Dan Williams
2018-01-06 10:06 ` Sergei Shtylyov
2018-01-09 3:11 ` Eric W. Biederman
2018-01-09 3:42 ` Dan Williams
2018-01-09 4:13 ` Linus Torvalds
2018-01-09 4:21 ` Linus Torvalds
2018-01-10 0:48 ` Dan Williams
2018-01-10 1:33 ` Dan Williams
2018-01-10 1:57 ` Alexei Starovoitov
2018-01-10 2:22 ` Dan Williams
2018-01-10 3:07 ` Alexei Starovoitov
2018-01-10 3:27 ` Linus Torvalds
2018-01-09 16:17 ` Eric W. Biederman
2018-01-09 18:01 ` Dan Williams
2018-01-10 0:54 ` Eric W. Biederman
2018-01-10 1:31 ` Dan Williams
2018-01-06 1:11 ` [PATCH 17/18] udf: " Dan Williams
2018-01-08 10:20 ` Jan Kara
2018-01-06 1:11 ` [PATCH 18/18] userns: " Dan Williams
2018-01-06 2:22 ` [PATCH 00/18] " Eric W. Biederman
2018-01-06 6:30 ` Dan Williams
2018-01-08 10:08 ` Peter Zijlstra
2018-01-08 11:14 ` Laurent Pinchart
2018-01-08 11:43 ` Alan Cox
2018-01-08 11:55 ` Peter Zijlstra
2018-01-08 18:33 ` Ingo Molnar
2018-01-08 16:20 ` Bart Van Assche
2018-01-06 18:56 ` Florian Fainelli
2018-01-06 18:59 ` Arjan van de Ven
2018-01-06 19:37 ` Dan Williams
2018-01-06 20:07 ` Dan Williams
2018-01-08 4:49 ` Bart Van Assche
2018-01-08 13:33 ` Arjan van de Ven
2018-01-09 19:34 ` Jiri Kosina
2018-01-09 19:44 ` Dan Williams
2018-01-09 20:55 ` Josh Poimboeuf
2018-01-11 9:54 ` Jiri Kosina
2018-01-11 15:58 ` Dan Williams
2018-01-11 16:34 ` Daniel Borkmann
2018-01-13 11:33 ` QingFeng Hao
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAPcyv4jn3O-qLKMgpTj0M+U98rO6M09p2XCxQggVVtWnAGBnYQ@mail.gmail.com \
--to=dan.j.williams@intel.com \
--cc=alan@linux.intel.com \
--cc=elena.reshetova@intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=laurent.pinchart@ideasonboard.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).