Executive brief
The Xilinx True Random Number Generator (TRNG) driver in the Linux kernel contained two bugs in its random number generation function: it could return success without filling the requested buffer completely, and concurrent access from different code paths could cause the same buffer to be accessed simultaneously without proper synchronization. This could lead to incomplete or corrupted random data being used for cryptographic operations.
Technical details
The vulnerability exists in the crypto_rng interface implementation of the Xilinx TRNG driver. The xtrng_trng_generate() function could return success even when it did not fill in all requested bytes, and concurrent execution with xtrng_hwrng_trng_read() was possible due to broken mutex locking logic. The root cause was improper synchronization and incomplete validation in the crypto_rng code path, which was removed entirely in the fix. The patch removes the unused crypto_rng interface (keeping only the hwrng interface which is properly used) and eliminates the faulty concurrent access scenario. The vulnerability affects systems using Xilinx Versal SoC where the TRNG crypto interface was invoked.
Affected products
- Linux Linux kernel all versions from initial addition in commit 8979744aca80 through versions prior to the fix
Timeline
- 2026-05-31: disclosed: Patch committed by Eric Biggers
- 2026-06-11: patched: Merged into mainline by Herbert Xu
- 2026-09-04: advisory