drm/mediatek: Add missing IS_ERR check for ovl_adaptor platform devicegrafted

platform_device_register_data() can fail and return an ERR_PTR, but the
return value is used without checking, leading to an invalid pointer
being stored in ddp_comp[].dev and passed to component_match_add() and
mtk_ddp_comp_init(), which could result in a kernel crash.

Add an IS_ERR() check to jump to the error handling path on failure.

Fixes: 0d9eee9118b7 ("drm/mediatek: Add drm ovl_adaptor sub driver for MT8195")
Cc: stable@vger.kernel.org
Signed-off-by: Haojie Li <lihaojie@kylinos.cn>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20260825100845.438893-1-lihaojie@kylinos.cn/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/Documentation/filesystems/devpts.rst b/Documentation/filesystems/devpts.rst
new file mode 100644
index 000000000..b6324ab19
--- /dev/null
+++ b/Documentation/filesystems/devpts.rst
@@ -0,0 +1,36 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+The Devpts Filesystem
+=====================
+
+Each mount of the devpts filesystem is now distinct such that ptys
+and their indices allocated in one mount are independent from ptys
+and their indices in all other mounts.
+
+All mounts of the devpts filesystem now create a ``/dev/pts/ptmx`` node
+with permissions ``0000``.
+
+To retain backwards compatibility the a ptmx device node (aka any node
+created with ``mknod name c 5 2``) when opened will look for an instance
+of devpts under the name ``pts`` in the same directory as the ptmx device
+node.
+
+As an option instead of placing a ``/dev/ptmx`` device node at ``/dev/ptmx``
+it is possible to place a symlink to ``/dev/pts/ptmx`` at ``/dev/ptmx`` or
+to bind mount ``/dev/ptx/ptmx`` to ``/dev/ptmx``.  If you opt for using
+the devpts filesystem in this manner devpts should be mounted with
+the ``ptmxmode=0666``, or ``chmod 0666 /dev/pts/ptmx`` should be called.
+
+Total count of pty pairs in all instances is limited by sysctls::
+
+    kernel.pty.max = 4096	- global limit
+    kernel.pty.reserve = 1024	- reserved for filesystems mounted from the initial mount namespace
+    kernel.pty.nr		- current count of ptys
+
+Per-instance limit could be set by adding mount option ``max=<count>``.
+
+This feature was added in kernel 3.4 together with
+``sysctl kernel.pty.reserve``.
+
+In kernels older than 3.4 sysctl ``kernel.pty.max`` works as per-instance limit.