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CVE-2026-45894 — iommu/vt-d: Clear Present bit before tearing down PASID entry

2026-10-13T05:40:01.466883+00:00

Affected: Linux

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

iommu/vt-d: Clear Present bit before tearing down PASID entry

The Intel VT-d Scalable Mode PASID table entry consists of 512 bits (64 bytes). When tearing down an entry, the current implementation zeros the entire 64-byte structure immediately using multiple 64-bit writes.

Since the IOMMU hardware may fetch these 64 bytes using multiple internal transactions (e.g., four 128-bit bursts), updating or zeroing the entire entry while it is active (P=1) risks a "torn" read. If a hardware fetch occurs simultaneously with the CPU zeroing the entry, the hardware could observe an inconsistent state, leading to unpredictable behavior or spurious faults.

Follow the "Guidance to Software for Invalidations" in the VT-d spec (Section 6.5.3.3) by implementing the recommended ownership handshake:

1. Clear only the 'Present' (P) bit of the PASID entry. 2. Use a dma_wmb() to ensure the cleared bit is visible to hardware before proceeding. 3. Execute the required invalidation sequence (PASID cache, IOTLB, and Device-TLB flush) to ensure the hardware has released all cached references. 4. Only after the flushes are complete, zero out the remaining fields of the PASID entry.

Also, add a dma_wmb() in pasid_set_present() to ensure that all other fields of the PASID entry are visible to the hardware before the Present bit is set.

USN-8781-1 — linux-nvidia-tegra vulnerabilities

2026-10-13T05:40:01.466948+00:00

Affected: Ubuntu:24.04:LTS: linux-nvidia-tegra

It was discovered that some Arm processors could complete a broadcast translation lookaside buffer (TLB) invalidation before memory writes made through the invalidated translation were globally observed. A local attacker could possibly use this to write to memory after permission to do so had been revoked, bypassing memory protections or escalating privileges. (CVE-2025-10263)

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; - User-space API (UAPI); - Kernel build system; - ARM32 architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - User-Mode Linux (UML); - x86 architecture; - Cryptographic API; - Intel NPU Driver; - Compute Acceleration Framework; - ACPI drivers; - Drivers core; - DRBD Distributed Replicated Block Device drivers; - Rados block device (RBD) driver; - Ublk userspace block driver; - Compressed RAM block device driver; - Bluetooth drivers; - Hardware crypto device drivers; - CXL (Compute Express Link) drivers; - Arm Firmware Framework for ARMv8-A(FFA); - EFI core; - FPGA Framework; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - I3C subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Mouse) drivers; - IOMMU subsystem; - Multiple devices driver; - Media…