target/linux/generic/backport-5.15/750-v6.5-20-net-ethernet-mtk_eth_soc-fix-uninitialized-variable.patch

   1 From e10a35abb3da12b812cfb6fc6137926a0c81e39a Mon Sep 17 00:00:00 2001
   2 From: Daniel Golle <daniel@makrotopia.org>
   3 Date: Sun, 10 Sep 2023 22:40:30 +0100
   4 Subject: [PATCH] net: ethernet: mtk_eth_soc: fix uninitialized variable
   5
   6 Variable dma_addr in function mtk_poll_rx can be uninitialized on
   7 some of the error paths. In practise this doesn't matter, even random
   8 data present in uninitialized stack memory can safely be used in the
   9 way it happens in the error path.
  10
  11 However, in order to make Smatch happy make sure the variable is
  12 always initialized.
  13
  14 Signed-off-by: Daniel Golle <daniel@makrotopia.org>
  15 Signed-off-by: David S. Miller <davem@davemloft.net>
  16 ---
  17  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 5 +++--
  18  1 file changed, 3 insertions(+), 2 deletions(-)
  19
  20 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  21 +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  22 @@ -1941,11 +1941,11 @@ static int mtk_poll_rx(struct napi_struc
  23         u8 *data, *new_data;
  24         struct mtk_rx_dma_v2 *rxd, trxd;
  25         int done = 0, bytes = 0;
  26 +       dma_addr_t dma_addr = DMA_MAPPING_ERROR;
  27
  28         while (done < budget) {
  29                 unsigned int pktlen, *rxdcsum;
  30                 struct net_device *netdev;
  31 -               dma_addr_t dma_addr;
  32                 u32 hash, reason;
  33                 int mac = 0;
  34
  35 @@ -2122,7 +2122,8 @@ release_desc:
  36                 else
  37                         rxd->rxd2 = RX_DMA_PREP_PLEN0(ring->buf_size);
  38
  39 -               if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA))
  40 +               if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA) &&
  41 +                   likely(dma_addr != DMA_MAPPING_ERROR))
  42                         rxd->rxd2 |= RX_DMA_PREP_ADDR64(dma_addr);
  43
  44                 ring->calc_idx = idx;