Re: [PATCH net 1/1] net: dsa: mv88e6xxx: Fix out-of-bound access

[Andrew Lunn]

On Mon, Aug 19, 2024 at 06:26:40PM -0400, Joseph Huang wrote:
> If an ATU violation was caused by a CPU Load operation, the SPID is 0xf,
> which is larger than DSA_MAX_PORTS (the size of mv88e6xxx_chip.ports[]
> array).

The 6390X datasheet says "IF SPID = 0x1f the source of the violation
was the CPU's registers interface."

> +#define MV88E6XXX_G1_ATU_DATA_SPID_CPU				0x000f

So it seems to depend on the family.

>  
>  /* Offset 0x0D: ATU MAC Address Register Bytes 0 & 1
>   * Offset 0x0E: ATU MAC Address Register Bytes 2 & 3
> diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> index ce3b3690c3c0..b6f15ae22c20 100644
> --- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
> +++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> @@ -457,7 +457,8 @@ static irqreturn_t mv88e6xxx_g1_atu_prob_irq_thread_fn(int irq, void *dev_id)
>  		trace_mv88e6xxx_atu_full_violation(chip->dev, spid,
>  						   entry.portvec, entry.mac,
>  						   fid);
> -		chip->ports[spid].atu_full_violation++;
> +		if (spid != MV88E6XXX_G1_ATU_DATA_SPID_CPU)
> +			chip->ports[spid].atu_full_violation++;

So i think it would be better to do something like:

		if (spid < ARRAY_SIZE(chip->ports))
			chip->ports[spid].atu_full_violation++;

    Andrew

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