In the Linux kernel, the following vulnerability has been resolved:
crypto: jitterentropy - replace long-held spinlock with mutex
jent_kcapi_random() serializes the shared jitterentropy state, but it currently holds a spinlock across the jent_read_entropy() call. That path performs expensive jitter collection and SHA3 conditioning, so parallel readers can trigger stalls as contending waiters spin for the same lock.
To prevent non-preemptible lock hold, replace rng->jent_lock with a mutex so contended readers sleep instead of spinning on a shared lock held across expensive entropy generation.
References
- https://git.kernel.org/stable/c/01d798e9feb30212952d4e992801ba6bd6a82351
- https://git.kernel.org/stable/c/18216b8ab6904753eaf31baf453cb02ecd202ba4
- https://git.kernel.org/stable/c/4c03e6eb98443dc4d6d422a9780034a5b75376b4
- https://git.kernel.org/stable/c/ec427dc5286da1ed08f2d510e2147a7581b0cb02
- https://git.kernel.org/stable/c/ff734dbd9e2432601a6dcd167cfb0bf8a36d1880