CVE-2024-35875 — x86/coco: Require seeding RNG with RDRAND on CoCo systems

Affected: Linux

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

x86/coco: Require seeding RNG with RDRAND on CoCo systems

There are few uses of CoCo that don't rely on working cryptography and hence a working RNG. Unfortunately, the CoCo threat model means that the VM host cannot be trusted and may actively work against guests to extract secrets or manipulate computation. Since a malicious host can modify or observe nearly all inputs to guests, the only remaining source of entropy for CoCo guests is RDRAND.

If RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole is meant to gracefully continue on gathering entropy from other sources, but since there aren't other sources on CoCo, this is catastrophic. This is mostly a concern at boot time when initially seeding the RNG, as after that the consequences of a broken RDRAND are much more theoretical.

So, try at boot to seed the RNG using 256 bits of RDRAND output. If this fails, panic(). This will also trigger if the system is booted without RDRAND, as RDRAND is essential for a safe CoCo boot.

Add this deliberately to be "just a CoCo x86 driver feature" and not part of the RNG itself. Many device drivers and platforms have some desire to contribute something to the RNG, and add_device_randomness() is specifically meant for this purpose.

Any driver can call it with seed data of any quality, or even garbage quality, and it can only possibly make the quality of the RNG better or have no effect, but can never…

USN-6893-1 — linux, linux-azure, linux-gcp, linux-ibm, linux-intel, linux-lowlatency, linux-oem-6.8, linux-raspi vulnerabilities

Affected: Ubuntu:24.04:LTS: linux, Ubuntu:24.04:LTS: linux-azure, Ubuntu:24.04:LTS: linux-gcp, Ubuntu:24.04:LTS: linux-ibm, Ubuntu:24.04:LTS: linux-intel, Ubuntu:24.04:LTS: linux-lowlatency, Ubuntu:24.04:LTS: linux-oem-6.8, Ubuntu:24.04:LTS: linux-raspi

It was discovered that a race condition existed in the Bluetooth subsystem in the Linux kernel when modifying certain settings values through debugfs. A privileged local attacker could use this to cause a denial of service. (CVE-2024-24857, CVE-2024-24858, CVE-2024-24859)

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; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Compute Acceleration Framework; - Accessibility subsystem; - Android drivers; - Drivers core; - Bluetooth drivers; - Clock framework and drivers; - Data acquisition framework and drivers; - Cryptographic API; - Buffer Sharing and Synchronization framework; - GPU drivers; - On-Chip Interconnect management framework; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - VMware VMCI Driver; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - Device tree and open firmware driver; - Chrome hardware platform drivers; - i.MX PM domains; - TI SCI PM domains driver; - S/390 drivers; - SCSI drivers; - SPI subsystem; - Thermal drivers; - TTY drivers; - USB subsystem; - Framebuffer layer; - BTRFS file system; - Network file system server daemon; - NILFS2 file system; - File systems infrastructure; - Pstore file system; - SMB…

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CVE-2024-35875 — x86/coco: Require seeding RNG with RDRAND on CoCo systems

USN-6893-1 — linux, linux-azure, linux-gcp, linux-ibm, linux-intel, linux-lowlatency, linux-oem-6.8, linux-raspi vulnerabilities