Ensure a valid XSK buffer before proceed to free the xdp buffer.

The following kernel panic is observed without this patch:

RIP: 0010:xp_free+0x5/0x40 Call Trace: stmmac_napi_poll_rxtx+0x332/0xb30 [stmmac] ? stmmac_tx_timer+0x3c/0xb0 [stmmac] net_rx_action+0x13d/0x3d0 __do_softirq+0xfc/0x2fb ? smpboot_register_percpu_thread+0xe0/0xe0 run_ksoftirqd+0x32/0x70 smpboot_thread_fn+0x1d8/0x2c0 kthread+0x169/0x1a0 ? kthread_park+0x90/0x90 ret_from_fork+0x1f/0x30 ---[ end trace 0000000000000002 ]---

Fixes: bba2556efad6 ("net: stmmac: Enable RX via AF_XDP zero-copy") Cc: stable@vger.kernel.org # 5.13.x Suggested-by: Ong Boon Leong boon.leong.ong@intel.com Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com --- v2 changelog: - Add stable@vger.kernel.org in email cc list. --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 7b8404a21544..fa90bcdf4e45 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -4914,6 +4914,10 @@ static int stmmac_rx_zc(struct stmmac_priv *priv, int limit, u32 queue)

prefetch(np);

+ /* Ensure a valid XSK buffer before proceed */ + if (!buf->xdp) + break; + if (priv->extend_desc) stmmac_rx_extended_status(priv, &priv->dev->stats, &priv->xstats, @@ -4934,10 +4938,6 @@ static int stmmac_rx_zc(struct stmmac_priv *priv, int limit, u32 queue) continue; }

- /* Ensure a valid XSK buffer before proceed */ - if (!buf->xdp) - break; - /* XSK pool expects RX frame 1:1 mapped to XSK buffer */ if (likely(status & rx_not_ls)) { xsk_buff_free(buf->xdp);