ath10k: fix possible bmi crash

While testing other things I've found that CE
items aren't cleared properly. This could lead to
null dereferences in BMI.

To prevent that make sure CE revoking clears the
nbytes value (which is used as a buffer completion
indication) and memset the entire CE ring data
shared between host and target when
(re)initializing.

Also make sure to check BMI xfer pointer and print
a splat instead of crashing the kernel.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/ce.c

@@ -558,6 +558,7 @@ int ath10k_ce_revoke_recv_next(struct ath10k_ce_pipe *ce_state,
 
 		/* sanity */
 		dest_ring->per_transfer_context[sw_index] = NULL;
+		desc->nbytes = 0;
 
 		/* Update sw_index */
 		sw_index = CE_RING_IDX_INCR(nentries_mask, sw_index);
@@ -835,6 +836,9 @@ static int ath10k_ce_init_src_ring(struct ath10k *ar,
 
 	nentries = roundup_pow_of_two(attr->src_nentries);
 
+	memset(src_ring->base_addr_owner_space, 0,
+	       nentries * sizeof(struct ce_desc));
+
 	src_ring->sw_index = ath10k_ce_src_ring_read_index_get(ar, ctrl_addr);
 	src_ring->sw_index &= src_ring->nentries_mask;
 	src_ring->hw_index = src_ring->sw_index;
@@ -869,6 +873,9 @@ static int ath10k_ce_init_dest_ring(struct ath10k *ar,
 
 	nentries = roundup_pow_of_two(attr->dest_nentries);
 
+	memset(dest_ring->base_addr_owner_space, 0,
+	       nentries * sizeof(struct ce_desc));
+
 	dest_ring->sw_index = ath10k_ce_dest_ring_read_index_get(ar, ctrl_addr);
 	dest_ring->sw_index &= dest_ring->nentries_mask;
 	dest_ring->write_index =

drivers/net/wireless/ath/ath10k/pci.c

@@ -1442,6 +1442,9 @@ static void ath10k_pci_bmi_recv_data(struct ath10k_ce_pipe *ce_state)
 					  &nbytes, &transfer_id, &flags))
 		return;
 
+	if (WARN_ON_ONCE(!xfer))
+		return;
+
 	if (!xfer->wait_for_resp) {
 		ath10k_warn(ar, "unexpected: BMI data received; ignoring\n");
 		return;