Wentao Liang 5148c7ea69 drm/amd/display: Add null pointer check for get_first_active_display()
commit c3e9826a22027a21d998d3e64882fa377b613006 upstream.

The function mod_hdcp_hdcp1_enable_encryption() calls the function
get_first_active_display(), but does not check its return value.
The return value is a null pointer if the display list is empty.
This will lead to a null pointer dereference in
mod_hdcp_hdcp2_enable_encryption().

Add a null pointer check for get_first_active_display() and return
MOD_HDCP_STATUS_DISPLAY_NOT_FOUND if the function return null.

Fixes: 2deade5ede ("drm/amd/display: Remove hdcp display state with mst fix")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org # v5.8
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-07-06 11:00:15 +02:00
2022-09-28 09:02:20 +02:00
2025-06-27 11:09:04 +01:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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