CVE-2026-90035

Description

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: fix division by zero in get_estimated_bw() get_estimated_bw() divides by link->dpia_bw_alloc_config.bw_granularity, which is zeroed by reset_bw_alloc_struct() and only populated once DP_TUNNELING_BW_ALLOC_CAP_CHANGED has been handled. link_dp_dpia_handle_bw_alloc_status(), the DPCD interrupt handler, calls get_estimated_bw() whenever DP_TUNNELING_ESTIMATED_BW_CHANGED is set, independently of whether DP_TUNNELING_BW_ALLOC_CAP_CHANGED has ever fired for that link. A connected USB4/DPIA tunneling device that reports an estimated-bandwidth change before ever reporting a capability change drives a division by zero in this IRQ path. link_dpia_send_bw_alloc_request() already guards the same bw_granularity division; add the identical guard here rather than introducing a new pattern. (cherry picked from commit f2a961457c33dc34223aad5c9e8971de34a4eed3)

References

• https://git.kernel.org/stable/c/4814f28c45f58a71a80d09b80a60da6a063b539a
• https://git.kernel.org/stable/c/4c5b61b9df6ab33b55f228e1b6579cefad11a9f7
• https://git.kernel.org/stable/c/ac2ab58a79bf2401ae8c5d1c030bf0a5a376f43a
• https://git.kernel.org/stable/c/b08c3d5ee7feadd821208f7c2c1ec02a16ce5878
• https://git.kernel.org/stable/c/f63de9054da858d57054474c32464106f8375e0d