commit cc99bc62ff6902688ee7bd3a7b25eefc620fbb6a upstream. Atm until the DPCD for a connector is read the max link rate and lane count params are invalid. If the connector is modeset, in intel_dp_compute_config(), intel_dp_common_len_rate_limit(max_link_rate) will return 0, leading to a intel_dp->common_rates[-1] access. Fix the above by making sure the max link params are always valid. The above access leads to an undefined behaviour by definition, though not causing a user visible problem to my best knowledge, see the previous patch why. Nevertheless it is an undefined behaviour and it triggers a BUG() in CONFIG_UBSAN builds, hence CC:stable. Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Acked-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20211018094154.1407705-4-imre.deak@intel.com (cherry picked from commit 9ad87de4735620ffc555592e8c5f580478fa3ed0) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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