CVE - CVE-2024-35875

CVE-ID
CVE-2024-35875	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
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 make it worse. Rather than trying to build something into the core of the RNG, consider the particular CoCo issue just a CoCo issue, and therefore separate it all out into driver (well, arch/platform) code. [ bp: Massage commit message. ]
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/08044b08b37528b82f70a87576c692b4e4b7716e URL:https://git.kernel.org/stable/c/08044b08b37528b82f70a87576c692b4e4b7716e MISC:https://git.kernel.org/stable/c/22943e4fe4b3a2dcbadc3d38d5bf840bbdbfe374 URL:https://git.kernel.org/stable/c/22943e4fe4b3a2dcbadc3d38d5bf840bbdbfe374 MISC:https://git.kernel.org/stable/c/453b5f2dec276c1bb4ea078bf8c0da57ee4627e5 URL:https://git.kernel.org/stable/c/453b5f2dec276c1bb4ea078bf8c0da57ee4627e5 MISC:https://git.kernel.org/stable/c/99485c4c026f024e7cb82da84c7951dbe3deb584 URL:https://git.kernel.org/stable/c/99485c4c026f024e7cb82da84c7951dbe3deb584
Assigning CNA
kernel.org
Date Record Created
20240517	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20240517)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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