From: Liviu Dudau <liviu.dudau@arm.com>
To: Zhou Qingyang <zhou1615@umn.edu>
Cc: kjlu@umn.edu, "James (Qian) Wang" <james.qian.wang@arm.com>,
Mihail Atanassov <mihail.atanassov@arm.com>,
Brian Starkey <brian.starkey@arm.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] drm/komeda: Fix an undefined behavior bug in komeda_plane_add()
Date: Wed, 1 Dec 2021 13:28:55 +0000 [thread overview]
Message-ID: <Yad4l3HXBRavsE0y@e110455-lin.cambridge.arm.com> (raw)
In-Reply-To: <20211201033704.32054-1-zhou1615@umn.edu>
On Wed, Dec 01, 2021 at 11:37:03AM +0800, Zhou Qingyang wrote:
> In komeda_plane_add(), komeda_get_layer_fourcc_list() is assigned to
> formats and used in drm_universal_plane_init().
> drm_universal_plane_init() passes formats to
> __drm_universal_plane_init(). __drm_universal_plane_init() further
> passes formats to memcpy() as src parameter, which could lead to an
> undefined behavior bug on failure of komeda_get_layer_fourcc_list().
>
> Fix this bug by adding a check of formats.
>
> 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_KOMEDA=m show no new warnings,
> and our static analyzer no longer warns about this code.
>
> Fixes: 61f1c4a8ab75 ("drm/komeda: Attach komeda_dev to DRM-KMS")
> Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
Thanks for the fix!
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Best regards,
Liviu
> ---
> Changes in v2
> - Use kfree and return instead of using 'goto'
>
> drivers/gpu/drm/arm/display/komeda/komeda_plane.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_plane.c b/drivers/gpu/drm/arm/display/komeda/komeda_plane.c
> index d63d83800a8a..aa193c58f4bf 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_plane.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_plane.c
> @@ -265,6 +265,10 @@ static int komeda_plane_add(struct komeda_kms_dev *kms,
>
> formats = komeda_get_layer_fourcc_list(&mdev->fmt_tbl,
> layer->layer_type, &n_formats);
> + if (!formats) {
> + kfree(kplane);
> + return -ENOMEM;
> + }
>
> err = drm_universal_plane_init(&kms->base, plane,
> get_possible_crtcs(kms, c->pipeline),
> --
> 2.25.1
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
prev parent reply other threads:[~2021-12-01 13:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 14:23 [PATCH] drm/komeda: Fix an undefined behavior bug in komeda_plane_add() Zhou Qingyang
2021-11-30 18:17 ` Liviu Dudau
2021-12-01 3:37 ` [PATCH v2] " Zhou Qingyang
2021-12-01 13:28 ` Liviu Dudau [this message]
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