linux-kernel - [PATCH v2] drm/komeda: Fix an undefined behavior bug in komeda_plane

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211201033704.32054-1-zhou1615@umn.edu>
Date:   Wed,  1 Dec 2021 11:37:03 +0800
From:   Zhou Qingyang <zhou1615@....edu>
To:     zhou1615@....edu
Cc:     kjlu@....edu, "James (Qian) Wang" <james.qian.wang@....com>,
        Liviu Dudau <liviu.dudau@....com>,
        Mihail Atanassov <mihail.atanassov@....com>,
        Brian Starkey <brian.starkey@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] drm/komeda: Fix an undefined behavior bug in komeda_plane_add()

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@....edu>
---
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