Re: [PATCH v6 6/9] net: of_net: Add of_get_nvmem_eui48() helper for EUI-48 lookup

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Replacing memcpy() with ether_addr_copy() imposes an unsafe 16-bit alignment requirement on the caller-provided addr buffer, which can trigger unaligned access faults (kernel panics) on strict-alignment architectures.
--

commit a4898c618dc4fdc91885d4184cdfd51af73fa946
Author: Loic Poulain <loic.poulain@oss.qualcomm.com>

net: of_net: Add of_get_nvmem_eui48() helper for EUI-48 lookup

This commit factors out the common NVMEM EUI-48 retrieval logic from
of_get_mac_address_nvmem() into a new helper. The original function
is updated to call the new helper, preserving the lookup behavior.

> diff --git a/net/core/of_net.c b/net/core/of_net.c
> --- a/net/core/of_net.c
> +++ b/net/core/of_net.c
[ ... ]
> @@ -75,27 +73,54 @@ int of_get_mac_address_nvmem(struct device_node *np, u8 *addr)
[ ... ]
> -	memcpy(addr, mac, ETH_ALEN);
> -	kfree(mac);
> +	ret = of_get_nvmem_eui48(np, "mac-address", mac);
> +	if (ret)
> +		return ret;
> +
> +	if (!is_valid_ether_addr(mac))
> +		return -EINVAL;
> +
> +	ether_addr_copy(addr, mac);
> +	return 0;
>  }

[Severity: High]
Will the use of ether_addr_copy() here cause an unaligned access fault on
strict-alignment architectures?

The original code used memcpy(), which handles unaligned destination pointers
safely. The ether_addr_copy() function requires both source and destination
pointers to be 16-bit aligned.

While the local mac buffer is explicitly aligned to 16 bits in this patch,
the destination addr buffer is provided by the caller. Callers like
of_get_ethdev_address() often allocate a 1-byte aligned array on the stack:

of_get_ethdev_address() {
        u8 addr[ETH_ALEN];
        
        ret = of_get_mac_address(np, addr);
        ...
}

Could this lead to kernel panics during device probe when the stack-allocated
addr buffer happens to be unaligned?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260629-block-as-nvmem-v6-0-f02513dcd46d@oss.qualcomm.com?part=6