[PATCH v4 1/3] net: ipv6: Add support for default gateway discovery.

[Sergei Antonov]

On Sat, 22 Apr 2023 at 03:08, <emohandesi at linux.microsoft.com> wrote:
>
> From: Ehsan Mohandesi <emohandesi at linux.microsoft.com>

Hello, Ehsan! Good patch, but one little change is needed.

> +struct icmp6_ra_prefix_info {
> +       u8      type;           /* Type is 3 for Prefix Information. */
> +       u8      len;            /* Len is 4 for Prefix Information. */
> +       /* The number of leading bits in the Prefix that are valid. */
> +       u8      prefix_len;
> +       u8      reserved1:6,    /* MUST be ignored by the receiver. */
> +               aac:1,          /* autonomous address-configuration flag */
> +       /* Indicates that this prefix can be used for on-link determination. */
> +               on_link:1;
> +       /*
> +        * The length of time in seconds that the prefix is valid for the
> +        * purpose of on-link determination.
> +        */
> +       __be32  valid_lifetime;
> +       /* The length of time addresses remain preferred. */
> +       __be32  preferred_lifetime;
> +       __be32  reserved2;      /* MUST be ignored by the receiver. */
> +       /*
> +        * Prefix is an IP address or a prefix of an IP address. The Prefix
> +        * Length field contains the number of valid leading bits in the prefix.
> +        * The bits in the prefix after the prefix length are reserved and MUST
> +        * be initialized to zero by the sender and ignored by the receiver.
> +        */
> +       struct in6_addr prefix;
> +};

Here it should end with:
} __packed;
Because this structure may be placed at a badly aligned offset within
a packet. For example, at offset 0x46 within Ethernet packet.

Other than that:
Tested-by: Sergei Antonov <saproj at gmail.com>
Reviewed-by: Sergei Antonov <saproj at gmail.com>