On 04/04/2012 04:17 AM, Thomas Graf wrote:
> getsockopt(..., SCTP_EVENTS, ...) performs a length check and returns
> an error if the user provides less bytes than the size of struct
> sctp_event_subscribe.
>
> Struct sctp_event_subscribe needs to be extended by an u8 for every
> new event or notification type that is added.
>
> This obviously makes getsockopt fail for binaries that are compiled
> against an older versions of <net/sctp/user.h> which do not contain
> all event types.
>
> This patch changes getsockopt behaviour to no longer return an error
> if not enough bytes are being provided by the user. Instead, it
> returns as much of sctp_event_subscribe as fits into the provided buffer.
>
> This leads to the new behavior that users see what they have been aware
> of at compile time.
>
> The setsockopt(..., SCTP_EVENTS, ...) API is already behaving like this.
>
> Signed-off-by: Thomas Graf <tgraf@xxxxxxx>
Acked-by: Vlad Yasevich <vladislav.yasevich@xxxxxx>
-vlad
> ---
> net/sctp/socket.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 06b42b7..92ba71d 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -4133,9 +4133,10 @@ static int sctp_getsockopt_disable_fragments(struct sock *sk, int len,
> static int sctp_getsockopt_events(struct sock *sk, int len, char __user *optval,
> int __user *optlen)
> {
> - if (len < sizeof(struct sctp_event_subscribe))
> + if (len <= 0)
> return -EINVAL;
> - len = sizeof(struct sctp_event_subscribe);
> + if (len > sizeof(struct sctp_event_subscribe))
> + len = sizeof(struct sctp_event_subscribe);
> if (put_user(len, optlen))
> return -EFAULT;
> if (copy_to_user(optval, &sctp_sk(sk)->subscribe, len))
>
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