From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
To: maarten.lankhorst@linux.intel.com, mripard@kernel.org,
tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch,
sumit.semwal@linaro.org, christian.koenig@amd.com
Cc: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
skhan@linuxfoundation.org, gregkh@linuxfoundation.org,
linux-kernel-mentees@lists.linuxfoundation.org,
emil.l.velikov@gmail.com
Subject: [PATCH v3 0/2] drm: address potential UAF bugs with drm_master ptrs
Date: Sun, 20 Jun 2021 19:03:25 +0800 [thread overview]
Message-ID: <20210620110327.4964-1-desmondcheongzx@gmail.com> (raw)
This patch series addresses potential use-after-free errors when dereferencing pointers to struct drm_master. These were identified after one such bug was caught by Syzbot in drm_getunique():
https://syzkaller.appspot.com/bug?id=148d2f1dfac64af52ffd27b661981a540724f803
The series is broken up into two patches:
1. Implement a locked version of drm_is_current_master() function that's used within drm_auth.c.
2. Identify areas in drm_lease.c where pointers to struct drm_master are dereferenced, and ensure that the master pointers are not freed during use.
Changes in v2 -> v3:
- Patch 1: Move the definition of drm_is_current_master and the _locked version higher up in drm_auth.c to avoid needing a forward declaration of drm_is_current_master_locked. As suggested by Daniel Vetter.
- Patch 2: Instead of leaking drm_device.master_mutex into drm_lease.c to protect drm_master pointers, add a new drm_file_get_master() function that returns drm_file->master while increasing its reference count, to prevent drm_file->master from being freed. As suggested by Daniel Vetter.
Changes in v1 -> v2:
- Patch 2: Move the lock and assignment before the DRM_DEBUG_LEASE in drm_mode_get_lease_ioctl, as suggested by Emil Velikov.
Desmond Cheong Zhi Xi (2):
drm: add a locked version of drm_is_current_master
drm: protect drm_master pointers in drm_lease.c
drivers/gpu/drm/drm_auth.c | 73 +++++++++++++++++++++++++++----------
drivers/gpu/drm/drm_lease.c | 57 ++++++++++++++++++++---------
include/drm/drm_auth.h | 1 +
include/drm/drm_file.h | 15 ++++++--
4 files changed, 107 insertions(+), 39 deletions(-)
--
2.25.1
next reply other threads:[~2021-06-20 11:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-20 11:03 Desmond Cheong Zhi Xi [this message]
2021-06-20 11:03 ` [PATCH v3 1/2] drm: add a locked version of drm_is_current_master Desmond Cheong Zhi Xi
2021-06-21 14:25 ` Daniel Vetter
2021-06-23 7:43 ` Daniel Vetter
2021-06-20 11:03 ` [PATCH v3 2/2] drm: protect drm_master pointers in drm_lease.c Desmond Cheong Zhi Xi
2021-06-21 14:47 ` Daniel Vetter
2021-06-23 3:48 ` Desmond Cheong Zhi Xi
2021-06-23 7:41 ` Daniel Vetter
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