[PATCH net v3 1/3] net: ti: icssg-prueth: Fix TX timestamp cleanup crash

[Meghana Malladi <m-malladi@ti.com>]

prueth_cleanup_tx_ts() incorrectly frees ERR_PTR(-EBUSY) slots. The TX
path reserves slots with ERR_PTR(-EBUSY) before storing the real skb
pointer. Use IS_ERR_OR_NULL() to skip these reserved slots during
cleanup, preventing NULL pointer dereference and freeing errors.

Fixes: e2dc7bfd677fc ("net: ti: icssg-prueth: Move common functions into a separate file")
Signed-off-by: Meghana Malladi <m-malladi@ti.com>
---

Changes from v2(v3-v2):
- Added this commit in the series which fixes the pre-existing issues
  flagged by sashiko

 drivers/net/ethernet/ti/icssg/icssg_common.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/ti/icssg/icssg_common.c b/drivers/net/ethernet/ti/icssg/icssg_common.c
index 4a7d1a6f470b..8cb2ad2ebece 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_common.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_common.c
@@ -1426,10 +1426,13 @@ void prueth_cleanup_tx_ts(struct prueth_emac *emac)
 	int i;
 
 	for (i = 0; i < PRUETH_MAX_TX_TS_REQUESTS; i++) {
-		if (emac->tx_ts_skb[i]) {
+		/* Slot may hold ERR_PTR(-EBUSY) if the TX path reserved it
+		 * but has not yet stored the real skb pointer.  Skip the free
+		 * but still clear the slot so it can be reused.
+		 */
+		if (!IS_ERR_OR_NULL(emac->tx_ts_skb[i]))
 			dev_kfree_skb_any(emac->tx_ts_skb[i]);
-			emac->tx_ts_skb[i] = NULL;
-		}
+		emac->tx_ts_skb[i] = NULL;
 	}
 }
 EXPORT_SYMBOL_GPL(prueth_cleanup_tx_ts);
-- 
2.43.0