CVE-2026-68329 — iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()

Affected: Linux

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

iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()

need_sync is a per-IOMMU flag shared by all domains and devices behind that IOMMU. It is set whenever a command is queued with sync == true and cleared when a completion-wait (CWAIT) command is queued. However, a cleared need_sync only means that a covering CWAIT has been queued, not that all previously queued commands have actually completed in hardware.

iommu_completion_wait() read need_sync locklessly and returned early when it was false. This breaks the "block until all previously queued commands have completed" contract in a multi-CPU scenario:

CPU2: queue inv-B => need_sync = true CPU1: queue CWAIT(N); need_sync = false; then wait_on_sem(N) CPU2: read need_sync == false => return 0 (no wait!)

CPU2 returns without waiting for any sequence number even though its inv-B may not have completed yet (CWAIT(N), queued after inv-B, has not been signaled). CPU2 then proceeds to, for example, free page-table pages while the IOMMU can still walk stale translations, opening a use-after-free window. This is a logical race in the meaning of the flag, not a memory-visibility issue, so barriers alone do not help.

Fix it without losing the optimization of avoiding redundant CWAIT commands: take iommu->lock before testing need_sync, and when it is false do not return early but wait for the last allocated…

USN-8886-1 — linux-nvidia-tegra vulnerabilities

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

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: - NVDIMM (Non-Volatile Memory Device) drivers; - Handshake API; - ARM32 architecture; - ARM64 architecture; - MIPS architecture; - OpenRISC architecture; - PowerPC architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Cryptographic API; - Intel NPU Driver; - Android drivers; - Rados block device (RBD) driver; - Bluetooth drivers; - Hardware random number generator core; - TPM device driver; - CPU frequency scaling framework; - Hardware crypto device drivers; - DMA engine subsystem; - FireWire subsystem; - Arm Firmware Framework for ARMv8-A(FFA); - GPIO subsystem; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - CoreSight HW tracing drivers; - I2C subsystem; - IIO ADC drivers; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Mouse) drivers; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - Multifunction device drivers; - Fastrpc Driver; - Amazon Nitro Secure Module driver; - MMC subsystem; - MTD block device drivers; - Ethernet bonding driver; - Network drivers; - Mellanox network drivers; - Texas Instruments network drivers; - NTB driver; - NVME drivers; - NVMEM (Non Volatile Memory) drivers; - Parport drivers…

Most recent entries from all

CVE-2026-68329 — iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()

USN-8886-1 — linux-nvidia-tegra vulnerabilities