During the PCI AER system's error recovery process, the kernel driver may encounter a race condition with freeing the reset_data structure's memory. If the device restart will take more than 10 seconds the function scheduling that restart will exit due to a timeout, and the reset_data structure will be freed. However, this data structure is used for completion notification after the restart is completed, which leads to a UAF bug.
This results in a KFENCE bug notice.
BUG: KFENCE: use-after-free read in adf_device_reset_worker+0x38/0xa0 [intel_qat] Use-after-free read at 0x00000000bc56fddf (in kfence-#142): adf_device_reset_worker+0x38/0xa0 [intel_qat] process_one_work+0x173/0x340
To resolve this race condition, the memory associated to the container of the work_struct is freed on the worker if the timeout expired, otherwise on the function that schedules the worker. The timeout detection can be done by checking if the caller is still waiting for completion or not by using completion_done() function.
Fixes: d8cba25d2c68 ("crypto: qat - Intel(R) QAT driver framework") Cc: stable@vger.kernel.org Signed-off-by: Damian Muszynski damian.muszynski@intel.com Reviewed-by: Giovanni Cabiddu giovanni.cabiddu@intel.com --- drivers/crypto/intel/qat/qat_common/adf_aer.c | 22 ++++++++++++++----- 1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/crypto/intel/qat/qat_common/adf_aer.c b/drivers/crypto/intel/qat/qat_common/adf_aer.c index 3597e7605a14..9da2278bd5b7 100644 --- a/drivers/crypto/intel/qat/qat_common/adf_aer.c +++ b/drivers/crypto/intel/qat/qat_common/adf_aer.c @@ -130,7 +130,8 @@ static void adf_device_reset_worker(struct work_struct *work) if (adf_dev_restart(accel_dev)) { /* The device hanged and we can't restart it so stop here */ dev_err(&GET_DEV(accel_dev), "Restart device failed\n"); - if (reset_data->mode == ADF_DEV_RESET_ASYNC) + if (reset_data->mode == ADF_DEV_RESET_ASYNC || + completion_done(&reset_data->compl)) kfree(reset_data); WARN(1, "QAT: device restart failed. Device is unusable\n"); return; @@ -146,11 +147,19 @@ static void adf_device_reset_worker(struct work_struct *work) adf_dev_restarted_notify(accel_dev); clear_bit(ADF_STATUS_RESTARTING, &accel_dev->status);
- /* The dev is back alive. Notify the caller if in sync mode */ - if (reset_data->mode == ADF_DEV_RESET_SYNC) - complete(&reset_data->compl); - else + /* + * The dev is back alive. Notify the caller if in sync mode + * + * If device restart will take a more time than expected, + * the schedule_reset() function can timeout and exit. This can be + * detected by calling the completion_done() function. In this case + * the reset_data structure needs to be freed here. + */ + if (reset_data->mode == ADF_DEV_RESET_ASYNC || + completion_done(&reset_data->compl)) kfree(reset_data); + else + complete(&reset_data->compl); }
static int adf_dev_aer_schedule_reset(struct adf_accel_dev *accel_dev, @@ -183,8 +192,9 @@ static int adf_dev_aer_schedule_reset(struct adf_accel_dev *accel_dev, dev_err(&GET_DEV(accel_dev), "Reset device timeout expired\n"); ret = -EFAULT; + } else { + kfree(reset_data); } - kfree(reset_data); return ret; } return 0;
base-commit: 86f2ff2d4ec09a7eea931a56fbed2105037ba2ee