In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Fix NULL pointer dereference in dcn401_init_hw()
dcn401_init_hw() assumes that update_bw_bounding_box() is valid when
entering the update path. However, the existing condition:
((!fams2_enable && update_bw_bounding_box) || freq_changed)
does not guarantee this, as the freq_changed branch can evaluate to true
independently of the callback pointer.
This can result in calling update_bw_bounding_box() when it is NULL.
Fix this by separating the update condition from the pointer checks and
ensuring the callback, dc->clk_mgr, and bw_params are validated before
use.
Fixes the below:
../dc/hwss/dcn401/dcn401_hwseq.c:367 dcn401_init_hw() error: we previously assumed 'dc->res_pool->funcs->update_bw_bounding_box' could be null (see line 362)
(cherry picked from commit 86117c5ab42f21562fedb0a64bffea3ee5fcd477)