In the Linux kernel, the following vulnerability has been resolved:
crypto: atmel-sha204a - fix heap info leak on I2C transfer failure
The nonblocking RNG path allocates a work_data structure to track the state of an in-flight asynchronous I2C request. This pointer is stored in rng->priv and later consumed by the read path once the transaction completes.
If the underlying I2C transfer fails, the completion callback is invoked with a non-zero status. In this case, the allocated work_data is not usable for producing RNG output and must not remain associated with the hwrng state.
Previously, the failure path only logged a warning but left the pointer state uncleared, which can result in subsequent read attempts observing stale state and interpreting it as valid completion data.
Fix this by freeing the pending work_data. The I2C transaction reports an error. This ensures that failed requests do not leave residual state behind that could be interpreted as valid RNG data on later reads. Clearing rng->priv is done at the subsequent call to nonblocking read.