CVE-2025-71070 — ublk: clean up user copy references on ublk server exit

Affected: Linux

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

ublk: clean up user copy references on ublk server exit

If a ublk server process releases a ublk char device file, any requests dispatched to the ublk server but not yet completed will retain a ref value of UBLK_REFCOUNT_INIT. Before commit e63d2228ef83 ("ublk: simplify aborting ublk request"), __ublk_fail_req() would decrement the reference count before completing the failed request. However, that commit optimized __ublk_fail_req() to call __ublk_complete_rq() directly without decrementing the request reference count. The leaked reference count incorrectly allows user copy and zero copy operations on the completed ublk request. It also triggers the WARN_ON_ONCE(refcount_read(&io->ref)) warnings in ublk_queue_reinit() and ublk_deinit_queue(). Commit c5c5eb24ed61 ("ublk: avoid ublk_io_release() called after ublk char dev is closed") already fixed the issue for ublk devices using UBLK_F_SUPPORT_ZERO_COPY or UBLK_F_AUTO_BUF_REG. However, the reference count leak also affects UBLK_F_USER_COPY, the other reference-counted data copy mode. Fix the condition in ublk_check_and_reset_active_ref() to include all reference-counted data copy modes. This ensures that any ublk requests still owned by the ublk server when it exits have their reference counts reset to 0.

USN-8177-1 — linux, linux-realtime vulnerabilities

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

Josh Eads, Kristoffer Janke, Eduardo Vela Nava, Tavis Ormandy, and Matteo Rizzo discovered that some AMD Zen processors did not properly verify the signature of CPU microcode. This flaw is known as EntrySign. A privileged attacker could possibly use this issue to cause load malicious CPU microcode causing loss of integrity and confidentiality. (CVE-2024-36347)

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: - MIPS architecture; - PowerPC architecture; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Cryptographic API; - ACPI drivers; - Ublk userspace block driver; - Bluetooth drivers; - Character device driver; - TPM device driver; - Clock framework and drivers; - GPU drivers; - Hardware monitoring drivers; - Intel Trace Hub HW tracing drivers; - InfiniBand drivers; - Input Device core drivers; - Input Device (Mouse) drivers; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - Network drivers; - Mellanox network drivers; - STMicroelectronics network drivers; - Ethernet team driver; - PA-RISC drivers; - Chrome hardware platform drivers; - x86 platform drivers; - SCSI subsystem; - SPI subsystem; - TCM subsystem; - Freescale USB OTG Transceiver Driver; - USB Type-C Connector System Software Interface driver; - Watchdog drivers; - BTRFS file sy…

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CVE-2025-71070 — ublk: clean up user copy references on ublk server exit

USN-8177-1 — linux, linux-realtime vulnerabilities