[PATCH net v4] net: xilinx: axienet: Fix IRQ coalescing packet count overflow

[PATCH net v4] net: xilinx: axienet: Fix IRQ coalescing packet count overflow

[Sean Anderson]

If coalece_count is greater than 255 it will not fit in the register and
will overflow. This can be reproduced by running

    # ethtool -C ethX rx-frames 256

which will result in a timeout of 0us instead. Fix this by checking for
invalid values and reporting an error.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Fixes: 8a3b7a252dca ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
---

Changes in v4:
- Fix checking rx twice instead of rx and tx

Changes in v3:
- Validate and reject instead of silently clamping

Changes in v2:
- Use FIELD_MAX to extract the max value from the mask
- Expand the commit message with an example on how to reproduce this
  issue

 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 0f4b02fe6f85..ae743991117c 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -2056,6 +2056,12 @@ axienet_ethtools_set_coalesce(struct net_device *ndev,
 		return -EBUSY;
 	}
 
+	if (ecoalesce->rx_max_coalesced_frames > 255 ||
+	    ecoalesce->tx_max_coalesced_frames > 255) {
+		NL_SET_ERR_MSG(extack, "frames must be less than 256");
+		return -EINVAL;
+	}
+
 	if (ecoalesce->rx_max_coalesced_frames)
 		lp->coalesce_count_rx = ecoalesce->rx_max_coalesced_frames;
 	if (ecoalesce->rx_coalesce_usecs)
-- 
2.35.1.1320.gc452695387.dirty

Re: [PATCH net v4] net: xilinx: axienet: Fix IRQ coalescing packet count overflow

[Nelson, Shannon]

On 1/10/2025 11:07 AM, Sean Anderson wrote:
> 
> If coalece_count is greater than 255 it will not fit in the register and

s/coalece_count/coalesce_count/

Otherwise looks fine.

Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>


> will overflow. This can be reproduced by running
> 
>      # ethtool -C ethX rx-frames 256
> 
> which will result in a timeout of 0us instead. Fix this by checking for
> invalid values and reporting an error.
> 
> Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
> Fixes: 8a3b7a252dca ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
> ---
> 
> Changes in v4:
> - Fix checking rx twice instead of rx and tx
> 
> Changes in v3:
> - Validate and reject instead of silently clamping
> 
> Changes in v2:
> - Use FIELD_MAX to extract the max value from the mask
> - Expand the commit message with an example on how to reproduce this
>    issue
> 
>   drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> index 0f4b02fe6f85..ae743991117c 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> @@ -2056,6 +2056,12 @@ axienet_ethtools_set_coalesce(struct net_device *ndev,
>                  return -EBUSY;
>          }
> 
> +       if (ecoalesce->rx_max_coalesced_frames > 255 ||
> +           ecoalesce->tx_max_coalesced_frames > 255) {
> +               NL_SET_ERR_MSG(extack, "frames must be less than 256");
> +               return -EINVAL;
> +       }
> +
>          if (ecoalesce->rx_max_coalesced_frames)
>                  lp->coalesce_count_rx = ecoalesce->rx_max_coalesced_frames;
>          if (ecoalesce->rx_coalesce_usecs)
> --
> 2.35.1.1320.gc452695387.dirty
> 
>