> -----Original Message-----
> From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Sent: Monday, November 27, 2023 6:28 PM
> To: Pandey, Radhey Shyam <radhey.shyam.pandey@xxxxxxx>
> Cc: kernel-janitors@xxxxxxxxxxxxxxx
> Subject: [bug report] net: axienet: Introduce dmaengine support
>
> Hello Radhey Shyam Pandey,
>
> The patch 6a91b846af85: "net: axienet: Introduce dmaengine support"
> from Nov 16, 2023 (linux-next), leads to the following Smatch static checker
> warning:
>
> drivers/net/ethernet/xilinx/xilinx_axienet_main.c:1060
> axienet_dma_rx_cb()
> error: 'app_metadata' dereferencing possible ERR_PTR()
>
> drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> 1045 static void axienet_dma_rx_cb(void *data, const struct
> dmaengine_result *result)
> 1046 {
> 1047 struct skbuf_dma_descriptor *skbuf_dma;
> 1048 size_t meta_len, meta_max_len, rx_len;
> 1049 struct axienet_local *lp = data;
> 1050 struct sk_buff *skb;
> 1051 u32 *app_metadata;
> 1052
> 1053 skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_tail++);
> 1054 skb = skbuf_dma->skb;
> 1055 app_metadata =
> dmaengine_desc_get_metadata_ptr(skbuf_dma->desc, &meta_len,
> 1056 &meta_max_len);
>
> dmaengine_desc_get_metadata_ptr() can return error pointers
I will send out a patch to fix and add error handling for
dmaengine_desc_get_metadata_ptr().
>
> 1057 dma_unmap_single(lp->dev, skbuf_dma->dma_address, lp-
> >max_frm_size,
> 1058 DMA_FROM_DEVICE);
> 1059 /* TODO: Derive app word index programmatically */
> --> 1060 rx_len = (app_metadata[LEN_APP] & 0xFFFF);
> ^^^^^^^^^^^^
>
> 1061 skb_put(skb, rx_len);
> 1062 skb->protocol = eth_type_trans(skb, lp->ndev);
> 1063 skb->ip_summed = CHECKSUM_NONE;
> 1064
> 1065 __netif_rx(skb);
> 1066 u64_stats_update_begin(&lp->rx_stat_sync);
> 1067 u64_stats_add(&lp->rx_packets, 1);
> 1068 u64_stats_add(&lp->rx_bytes, rx_len);
> 1069 u64_stats_update_end(&lp->rx_stat_sync);
> 1070 axienet_rx_submit_desc(lp->ndev);
> 1071 dma_async_issue_pending(lp->rx_chan);
> 1072 }
>
> regards,
> dan carpenter
