From: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
To: Zhou Qingyang <zhou1615@umn.edu>
Cc: kjlu@umn.edu, David Airlie <airlied@linux.ie>,
Daniel Vetter <daniel@ffwll.ch>, Dave Airlie <airlied@redhat.com>,
Alan Cox <alan@linux.intel.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] drm/gma500/cdv_intel_lvds: Fix a wild pointer dereference in cdv_intel_lvds_get_modes()
Date: Thu, 2 Dec 2021 11:11:02 +0100 [thread overview]
Message-ID: <CAMeQTsazxeXgOJcuGZhEH5BX5ZzmOgM-NAjLjj9iypNgTqu-dg@mail.gmail.com> (raw)
In-Reply-To: <20211130132629.130713-1-zhou1615@umn.edu>
On Tue, Nov 30, 2021 at 2:26 PM Zhou Qingyang <zhou1615@umn.edu> wrote:
>
> In cdv_intel_lvds_get_modes(), the return value of drm_mode_duplicate()
> is assigned to mode and used in drm_mode_probed_add().
> drm_mode_probed_add() passes mode->head to list_add_tail().
> list_add_tail() will further call __list_add() and there is a
> dereference of mode->head in __list_add(), which could lead to a wild
> pointer dereference on failure of drm_mode_duplicate().
>
> Fix this bug by adding a checking of mode
>
> This bug was found by a static analyzer. The analysis employs
> differential checking to identify inconsistent security operations
> (e.g., checks or kfrees) between two code paths and confirms that the
> inconsistent operations are not recovered in the current function or
> the callers, so they constitute bugs.
>
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
>
> Builds with CONFIG_DRM_GMA500=m show no new warnings,
> and our static analyzer no longer warns about this code.
>
> Fixes: 6a227d5fd6c4 ("gma500: Add support for Cedarview")
> Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
> ---
> drivers/gpu/drm/gma500/cdv_intel_lvds.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/gma500/cdv_intel_lvds.c b/drivers/gpu/drm/gma500/cdv_intel_lvds.c
> index 9e1cdb11023c..56aec41ebb1a 100644
> --- a/drivers/gpu/drm/gma500/cdv_intel_lvds.c
> +++ b/drivers/gpu/drm/gma500/cdv_intel_lvds.c
> @@ -310,6 +310,9 @@ static int cdv_intel_lvds_get_modes(struct drm_connector *connector)
> if (mode_dev->panel_fixed_mode != NULL) {
> struct drm_display_mode *mode =
> drm_mode_duplicate(dev, mode_dev->panel_fixed_mode);
> + if (!mode)
> + return -ENOMEM;
> +
Same problem here as in the other patches.
> drm_mode_probed_add(connector, mode);
> return 1;
> }
> --
> 2.25.1
>
next prev parent reply other threads:[~2021-12-02 10:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 13:26 [PATCH] drm/gma500/cdv_intel_lvds: Fix a wild pointer dereference in cdv_intel_lvds_get_modes() Zhou Qingyang
2021-12-02 10:11 ` Patrik Jakobsson [this message]
2021-12-03 15:33 ` [PATCH v2] " Zhou Qingyang
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=CAMeQTsazxeXgOJcuGZhEH5BX5ZzmOgM-NAjLjj9iypNgTqu-dg@mail.gmail.com \
--to=patrik.r.jakobsson@gmail.com \
--cc=airlied@linux.ie \
--cc=airlied@redhat.com \
--cc=alan@linux.intel.com \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=kjlu@umn.edu \
--cc=linux-kernel@vger.kernel.org \
--cc=zhou1615@umn.edu \
/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).