From: Zhou Qingyang <zhou1615@umn.edu>
To: zhou1615@umn.edu
Cc: David Airlie <airlied@linux.ie>,
kjlu@umn.edu, Liviu Dudau <liviu.dudau@arm.com>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
"James \(Qian\) Wang" <james.qian.wang@arm.com>,
Mihail Atanassov <mihail.atanassov@arm.com>
Subject: [PATCH v2] drm/komeda: Fix an undefined behavior bug in komeda_plane_add()
Date: Wed, 1 Dec 2021 11:37:03 +0800 [thread overview]
Message-ID: <20211201033704.32054-1-zhou1615@umn.edu> (raw)
In-Reply-To: <YaZqt7bwSJtS2SaT@e110455-lin.cambridge.arm.com>
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>
---
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
next prev parent reply other threads:[~2021-12-01 3:37 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 ` Zhou Qingyang [this message]
2021-12-01 13:28 ` [PATCH v2] " Liviu Dudau
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=20211201033704.32054-1-zhou1615@umn.edu \
--to=zhou1615@umn.edu \
--cc=airlied@linux.ie \
--cc=dri-devel@lists.freedesktop.org \
--cc=james.qian.wang@arm.com \
--cc=kjlu@umn.edu \
--cc=linux-kernel@vger.kernel.org \
--cc=liviu.dudau@arm.com \
--cc=mihail.atanassov@arm.com \
/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).