CVE-2026-93068: drm/amd/display: Fix DM I2C teardown race

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix DM I2C teardown race DM I2C adapters can remain visible to userspace while DM teardown is already in progress. A concurrent i2c-dev transfer may then enter amdgpu_dm_i2c_xfer() after the backing DM state has been torn down, leading to a NULL pointer dereference. Create a devres group around the DM I2C adapter lifetime and release it at the start of dm_hw_fini(), before HPD, IRQ, and DM state are torn down. This removes the I2C adapters first and waits for in-flight users to drain before the structures used by amdgpu_dm_i2c_xfer() disappear. This fixes a teardown ordering race seen during device removal: BUG: kernel NULL pointer dereference RIP: amdgpu_dm_i2c_xfer+0x122/0x1c0 [amdgpu] Call Trace: __i2c_transfer i2c_transfer i2cdev_ioctl_rdwr