[PATCH net v1] mac802154: avoid extra skb references in RX queues

[Xuanqiang Luo <xuanqiang.luo@linux.dev>]

From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

__ieee802154_rx_handle_packet() passes each cloned skb to
ieee802154_subif_frame() and does not release it after the call. The
callee consumes the skb on every path: it either frees it, hands it to
the networking stack, or stores it in a queued RX descriptor.

The beacon and MAC command paths nevertheless call skb_get() before
storing the skb. The worker drops only that additional reference, leaving
the original clone reference without an owner and leaking every queued
skb.

kmemleak report:

unreferenced object 0xffff0000c1fcd480 (size 232):
  comm "softirq", pid 0, jiffies 4295683396
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 60 fd d4 00 00 ff ff 00 00 00 00 00 00 00 00  .`..............
  backtrace (crc ee03f6a1):
    kmemleak_alloc+0xcc/0xf8
    kmem_cache_alloc_noprof+0x240/0x418
    skb_clone+0x60/0xe0
    ieee802154_rx+0x19c/0x280 [mac802154]
    ieee802154_tasklet_handler+0xa8/0xb8 [mac802154]
    tasklet_action_common+0x148/0x528
    tasklet_action+0x38/0x50
    handle_softirqs+0x10c/0x450
    __do_softirq+0x1c/0x28

Transfer the existing skb reference to the descriptor instead of taking
another one.

Fixes: 57588c71177f ("mac802154: Handle passive scanning")
Fixes: d021d218f6d9 ("mac802154: Handle received BEACON_REQ")
Cc: stable@vger.kernel.org
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
---
 net/mac802154/rx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mac802154/rx.c b/net/mac802154/rx.c
index 19b5382e85a84..ad602d222e861 100644
--- a/net/mac802154/rx.c
+++ b/net/mac802154/rx.c
@@ -287,7 +287,7 @@ ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
 		if (!mac_pkt)
 			goto fail;
 
-		mac_pkt->skb = skb_get(skb);
+		mac_pkt->skb = skb;
 		mac_pkt->sdata = sdata;
 		mac_pkt->page = sdata->local->scan_page;
 		mac_pkt->channel = sdata->local->scan_channel;
@@ -304,7 +304,7 @@ ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
 		if (!mac_pkt)
 			goto fail;
 
-		mac_pkt->skb = skb_get(skb);
+		mac_pkt->skb = skb;
 		mac_pkt->sdata = sdata;
 		netdev_hold(sdata->dev, &mac_pkt->dev_tracker, GFP_ATOMIC);
 		spin_lock(&sdata->local->rx_lock);
-- 
2.43.0