[PATCH iwl-net v1] igc: fix potential skb leak in igc_fpe_xmit_smd_frame()

[Kohei Enju <kohei@enjuk.jp>]

When igc_fpe_init_tx_descriptor() fails, no one takes care of an
allocated skb, leaking it. [1]

Use dev_kfree_skb_any() on failure.
Also call igc_flush_tx_descriptors() only on success.

[1]
unreferenced object 0xffff88813aee1b40 (size 224):
  comm "softirq", pid 0, jiffies 4294709256
[...]
  backtrace (crc dee31384):
    kmem_cache_alloc_node_noprof+0x54f/0x640
    __alloc_skb+0xd9/0x5b0
    igc_fpe_xmit_smd_frame.isra.0+0xad/0x510
    igc_fpe_send_mpacket+0x32/0x80
[...]

Fixes: 5422570c0010 ("igc: add support for frame preemption verification")
Signed-off-by: Kohei Enju <kohei@enjuk.jp>
---
 drivers/net/ethernet/intel/igc/igc_tsn.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 8a110145bfee..eaa274248d54 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -109,10 +109,14 @@ static int igc_fpe_xmit_smd_frame(struct igc_adapter *adapter,
 	__netif_tx_lock(nq, cpu);
 
 	err = igc_fpe_init_tx_descriptor(ring, skb, type);
-	igc_flush_tx_descriptors(ring);
+	if (!err)
+		igc_flush_tx_descriptors(ring);
 
 	__netif_tx_unlock(nq);
 
+	if (err)
+		dev_kfree_skb_any(skb);
+
 	return err;
 }
 
-- 
2.51.0