[PATCH ath-next 1/2] wifi: ath12k: fix dp_link_peer dangling references on AP vdev rollback

[Baochen Qiang]

ath12k_mac_vdev_create() for an AP vdev creates the bss self-peer via
ath12k_peer_create(), which finishes by calling
ath12k_dp_link_peer_assign() to publish the dp_link_peer in the
dp_hw->dp_peers[peerid_index] RCU table, in the dp_peer's
link_peers[] array, and in the per-addr rhashtable.

If a step after ath12k_peer_create() fails the function jumps to
err_peer_del, which open-codes a WMI peer_delete and waits for the
unmap / delete_resp events. The wait_for_peer_delete_done() path
relies on ath12k_dp_link_peer_unmap_event() freeing the dp_link_peer
when the unmap arrives, but err_peer_del never calls
ath12k_dp_link_peer_unassign() first. The published references in
the dp_hw RCU table, dp_peer->link_peers[] and the rhashtable are
left pointing at the dp_link_peer that unmap_event then frees,
producing dangling pointers and use-after-free on subsequent
lookups.

Replace the open-coded sequence with a call to ath12k_peer_delete(),
which already does ath12k_dp_link_peer_unassign() before sending the
WMI command. This drops the published references before the
dp_link_peer is freed, in the same order as the normal teardown path
in ath12k_mac_remove_link_interface().

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3

Fixes: 5525f12fa671 ("wifi: ath12k: Attach and detach ath12k_dp_link_peer to ath12k_dp_peer")
Signed-off-by: Baochen Qiang <baochen.qiang at oss.qualcomm.com>
---
 drivers/net/wireless/ath/ath12k/mac.c | 18 ++----------------
 1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/wireless/ath/ath12k/mac.c
index af354bef5c0d..2e5a075191ae 100644
--- a/drivers/net/wireless/ath/ath12k/mac.c
+++ b/drivers/net/wireless/ath/ath12k/mac.c
@@ -10564,22 +10564,8 @@ int ath12k_mac_vdev_create(struct ath12k *ar, struct ath12k_link_vif *arvif)
 
 err_peer_del:
 	if (ahvif->vdev_type == WMI_VDEV_TYPE_AP) {
-		reinit_completion(&ar->peer_delete_done);
-
-		ret = ath12k_wmi_send_peer_delete_cmd(ar, arvif->bssid,
-						      arvif->vdev_id);
-		if (ret) {
-			ath12k_warn(ar->ab, "failed to delete peer vdev_id %d addr %pM\n",
-				    arvif->vdev_id, arvif->bssid);
-			goto err_dp_peer_del;
-		}
-
-		ret = ath12k_wait_for_peer_delete_done(ar, arvif->vdev_id,
-						       arvif->bssid);
-		if (ret)
-			goto err_dp_peer_del;
-
-		ar->num_peers--;
+		/* ignore return value: propagate the original error */
+		ath12k_peer_delete(ar, arvif->vdev_id, arvif->bssid);
 	}
 
 err_dp_peer_del:

-- 
2.25.1