From: Krzysztof Grzywocz
> Sent: 08 October 2018 20:07
>
> Problem:
> On 64bit kernel ELF32bit gets improper value of `SCTP_GET_ASSOC_STATS` (call `getsockopt` on SCTP
> socket) due to different `struct sctp_assoc_stats` aligment (mostly because of different
> `_K_SS_ALIGNSIZE`).
...
> -----
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index ce620e87..73963062 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -6685,6 +6685,65 @@ static int sctp_getsockopt_paddr_thresholds(struct sock *sk,
> return 0;
> }
>
> +#ifdef CONFIG_COMPAT
> +
> +struct __kernel_sockaddr_storage_compat32 {
> + __kernel_sa_family_t ss_family; /* address family */
> + /* Following field(s) are implementation specific */
> + char __data[_K_SS_MAXSIZE - sizeof(unsigned short)];
> + /* space to achieve desired size, */
> + /* _SS_MAXSIZE value minus size of ss_family */
> +} __attribute__ ((packed,aligned(4))); /* force desired alignment */
I don't think you need the attribute here.
You could also use an unnamed union. probably:
struct __kernel_sockaddr_storage_compat32 {
union {
__kernel_sa_family_t ss_family; /* address family */
char __data[_K_SS_MAXSIZE]; /* Pad to correct size */
}
};
> +struct sctp_assoc_stats_compat32 {
> + int32_t sas_assoc_id; /* Input */
> + /* Transport of observed max RTO */
> + struct __kernel_sockaddr_storage_compat32 sas_obs_rto_ipaddr;
> + uint64_t sas_maxrto; /* Maximum Observed RTO for period */
> + uint64_t sas_isacks; /* SACKs received */
> + uint64_t sas_osacks; /* SACKs sent */
> + uint64_t sas_opackets; /* Packets sent */
> + uint64_t sas_ipackets; /* Packets received */
> + uint64_t sas_rtxchunks; /* Retransmitted Chunks */
> + uint64_t sas_outofseqtsns;/* TSN received > next expected */
> + uint64_t sas_idupchunks; /* Dups received (ordered+unordered) */
> + uint64_t sas_gapcnt; /* Gap Acknowledgements Received */
> + uint64_t sas_ouodchunks; /* Unordered data chunks sent */
> + uint64_t sas_iuodchunks; /* Unordered data chunks received */
> + uint64_t sas_oodchunks; /* Ordered data chunks sent */
> + uint64_t sas_iodchunks; /* Ordered data chunks received */
> + uint64_t sas_octrlchunks; /* Control chunks sent */
> + uint64_t sas_ictrlchunks; /* Control chunks received */
> +} __attribute__ ((packed,aligned(4)));
Isn't there a 'uint64_t with the alignment needed for 32bit apps'
that can be used for the uint64_t structure members?
It will be needed for a lot of compat fields.
Then you don't need the attribute here either.
It would then be right for any 32bit architectures where u64 is 8
byte aligned.
David
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