In the Linux kernel, the following vulnerability has been resolved: drm/ast: Fix soft lockup There is a while-loop in ast_dp_set_on_off() that could lead to infinite-loop. This is because the register, VGACRI-Dx, checked in this API is a scratch register actually controlled by a MCU, named DPMCU, in BMC. These scratch registers are protected by scu-lock. If suc-lock is not off, DPMCU can not update these registers and then host will have soft lockup due to never updated status. DPMCU is used to control DP and relative registers to handshake with host's VGA driver. Even the most time-consuming task, DP's link training, is less than 100ms. 200ms should be enough.
https://git.kernel.org/stable/c/bc004f5038220b1891ef4107134ccae44be55109
https://git.kernel.org/stable/c/a81b2acd43e24e419f65df97348c76a5a1496066
https://git.kernel.org/stable/c/8a6fea3fcb577a543ef67683ca7105bde49a38fb
https://git.kernel.org/stable/c/35768baf0fdfc47ede42d899506bad78450e9294