CVE-2021-47444

In the Linux kernel, the following vulnerability has been resolved: drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read In commit e11f5bd8228f (“drm: Add support for DP 1.4 Compliance edid corruption test”) the function connector_bad_edid() started assuming that the memory for the EDID passed to it was big enough to hold edid[0x7e] + 1 blocks of data (1 extra for the base block). It completely ignored the fact that the function was passed num_blocks which indicated how much memory had been allocated for the EDID. Let’s fix this by adding a bounds check. This is important for handling the case where there’s an error in the first block of the EDID. In that case we will call connector_bad_edid() without having re-allocated memory based on edid[0x7e].