CVE-2026-43337drm/amd/display: Fix NULL pointer dereference in dcn401_init_hw()

Official description

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)

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/fcc51c81cb472eb460310c477460356dc4845ff7
• https://git.kernel.org/stable/c/10c13c111d0d7f8e101c742feff264fc98e3f9f7
• https://git.kernel.org/stable/c/2d4a6f0702c5211e0be8b688c5fc24f082ec74d6
• https://git.kernel.org/stable/c/e927b36ae18b66b49219eaa9f46edc7b4fdbb25e