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CVE-2025-40288 — drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices

Previously, APU platforms (and other scenarios with uninitialized VRAM managers) triggered a NULL pointer dereference in `ttm_resource_manager_usage()`. The root cause is not that the `struct ttm_resource_manager *man` pointer itself is NULL, but that `man->bdev` (the backing device pointer within the manager) remains uninitialized (NULL) on APUs—since APUs lack dedicated VRAM and do not fully set up VRAM manager structures. When `ttm_resource_manager_usage()` attempts to acquire `man->bdev->lru_lock`, it dereferences the NULL `man->bdev`, leading to a kernel OOPS.

1. **amdgpu_cs.c**: Extend the existing bandwidth control check in `amdgpu_cs_get_threshold_for_moves()` to include a check for `ttm_resource_manager_used()`. If the manager is not used (uninitialized `bdev`), return 0 for migration thresholds immediately—skipping VRAM-specific logic that would trigger the NULL dereference.

2. **amdgpu_kms.c**: Update the `AMDGPU_INFO_VRAM_USAGE` ioctl and memory info reporting to use a conditional: if the manager is used, return the real VRAM usage; otherwise, return 0. This avoids accessing `man->bdev` when it is NULL.

3. **amdgpu_virt.c**: Modify the vf2pf (virtual function to physical function) data write path. Use `ttm_resource_manager_used()` to check validity: if the manager is usable, calculate `fb_usage`…

USN-8029-1 — linux, linux-raspi, linux-realtime vulnerabilities

Affected: Ubuntu:25.10: linux, Ubuntu:25.10: linux-raspi, Ubuntu:25.10: linux-realtime

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - MIPS architecture; - Nios II architecture; - PA-RISC architecture; - RISC-V architecture; - S390 architecture; - Sun Sparc architecture; - x86 architecture; - Xtensa architecture; - Block layer subsystem; - Cryptographic API; - Compute Acceleration Framework; - ACPI drivers; - Drivers core; - Network block device driver; - Bluetooth drivers; - Bus devices; - Hardware random number generator core; - Character device driver; - Clock framework and drivers; - Data acquisition framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - CXL (Compute Express Link) drivers; - Device frequency scaling framework; - ARM SCMI message protocol; - GPIO subsystem; - GPU drivers; - Hardware monitoring drivers; - HW tracing; - InfiniBand drivers; - Input Device (Miscellaneous) drivers; - IOMMU subsystem; - ISDN/mISDN subsystem; - Mailbox framework; - Multiple devices driver; - Media drivers; - Fastrpc Driver; - PCI Endpoint Test driver; - VMware Balloon Driver; - MOST (Media Oriented Systems Transport) drivers; - Network drivers; - Mellanox network drivers; - STMicroelectronics network drivers; - NVME drivers; - PCI subsystem; - Performance monitor drivers; - Pin…