[SRU][F][PATCH 1/3] media: cec: abort if the current transmit was canceled

[Jacob Martin]

From: Hans Verkuil <hverkuil-cisco at xs4all.nl>

If a transmit-in-progress was canceled, then, once the transmit
is done, mark it as aborted and refrain from retrying the transmit.

To signal this situation the new transmit_in_progress_aborted field is
set to true.

The old implementation would just set adap->transmitting to NULL and
set adap->transmit_in_progress to false, but on the hardware level
the transmit was still ongoing. However, the framework would think
the transmit was aborted, and if a new transmit was issued, then
it could overwrite the HW buffer containing the old transmit with the
new transmit, leading to garbled data on the CEC bus.

Signed-off-by: Hans Verkuil <hverkuil-cisco at xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab at kernel.org>
(backported from commit 590a8e564c6eff7e77a84e728612f1269e3c0685)
[jacobmartin: initialize transmit_in_progress_aborted in directly in
__cec_s_phys_addr as cec_activate_cnt_{inc,dec} from 3813c932ed ("media:
cec: call enable_adap on s_log_addrs") are not present.]
CVE-2024-23848
Signed-off-by: Jacob Martin <jacob.martin at canonical.com>
---
 drivers/media/cec/cec-adap.c | 13 ++++++++++---
 include/media/cec.h          |  1 +
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c
index 94ddaca496c9..cda48e58557c 100644
--- a/drivers/media/cec/cec-adap.c
+++ b/drivers/media/cec/cec-adap.c
@@ -418,7 +418,7 @@ static void cec_flush(struct cec_adapter *adap)
 		cec_data_cancel(data, CEC_TX_STATUS_ABORTED);
 	}
 	if (adap->transmitting)
-		cec_data_cancel(adap->transmitting, CEC_TX_STATUS_ABORTED);
+		adap->transmit_in_progress_aborted = true;
 
 	/* Cancel the pending timeout work. */
 	list_for_each_entry_safe(data, n, &adap->wait_queue, list) {
@@ -569,6 +569,7 @@ int cec_thread_func(void *_adap)
 		if (data->attempts == 0)
 			data->attempts = attempts;
 
+		adap->transmit_in_progress_aborted = false;
 		/* Tell the adapter to transmit, cancel on error */
 		if (adap->ops->adap_transmit(adap, data->attempts,
 					     signal_free_time, &data->msg))
@@ -596,6 +597,8 @@ void cec_transmit_done_ts(struct cec_adapter *adap, u8 status,
 	struct cec_msg *msg;
 	unsigned int attempts_made = arb_lost_cnt + nack_cnt +
 				     low_drive_cnt + error_cnt;
+	bool done = status & (CEC_TX_STATUS_MAX_RETRIES | CEC_TX_STATUS_OK);
+	bool aborted = adap->transmit_in_progress_aborted;
 
 	dprintk(2, "%s: status 0x%02x\n", __func__, status);
 	if (attempts_made < 1)
@@ -616,6 +619,7 @@ void cec_transmit_done_ts(struct cec_adapter *adap, u8 status,
 		goto wake_thread;
 	}
 	adap->transmit_in_progress = false;
+	adap->transmit_in_progress_aborted = false;
 
 	msg = &data->msg;
 
@@ -636,8 +640,7 @@ void cec_transmit_done_ts(struct cec_adapter *adap, u8 status,
 	 * the hardware didn't signal that it retried itself (by setting
 	 * CEC_TX_STATUS_MAX_RETRIES), then we will retry ourselves.
 	 */
-	if (data->attempts > attempts_made &&
-	    !(status & (CEC_TX_STATUS_MAX_RETRIES | CEC_TX_STATUS_OK))) {
+	if (!aborted && data->attempts > attempts_made && !done) {
 		/* Retry this message */
 		data->attempts -= attempts_made;
 		if (msg->timeout)
@@ -652,6 +655,8 @@ void cec_transmit_done_ts(struct cec_adapter *adap, u8 status,
 		goto wake_thread;
 	}
 
+	if (aborted && !done)
+		status |= CEC_TX_STATUS_ABORTED;
 	data->attempts = 0;
 
 	/* Always set CEC_TX_STATUS_MAX_RETRIES on error */
@@ -1571,6 +1576,7 @@ void __cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr, bool block)
 		if (adap->needs_hpd || list_empty(&adap->devnode.fhs)) {
 			WARN_ON(adap->ops->adap_enable(adap, false));
 			adap->transmit_in_progress = false;
+			adap->transmit_in_progress_aborted = false;
 			wake_up_interruptible(&adap->kthread_waitq);
 		}
 		mutex_unlock(&adap->devnode.lock);
@@ -1581,6 +1587,7 @@ void __cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr, bool block)
 	mutex_lock(&adap->devnode.lock);
 	adap->last_initiator = 0xff;
 	adap->transmit_in_progress = false;
+	adap->transmit_in_progress_aborted = false;
 
 	if ((adap->needs_hpd || list_empty(&adap->devnode.fhs)) &&
 	    adap->ops->adap_enable(adap, true)) {
diff --git a/include/media/cec.h b/include/media/cec.h
index 4d59387bc61b..06f88f126828 100644
--- a/include/media/cec.h
+++ b/include/media/cec.h
@@ -187,6 +187,7 @@ struct cec_adapter {
 	struct list_head wait_queue;
 	struct cec_data *transmitting;
 	bool transmit_in_progress;
+	bool transmit_in_progress_aborted;
 
 	struct task_struct *kthread_config;
 	struct completion config_completion;
-- 
2.43.0