From: Thomas Graf Date: Tue, 3 Apr 2012 22:17:53 +0000 (+0000) Subject: sctp: Allow struct sctp_event_subscribe to grow without breaking binaries X-Git-Tag: v3.4-rc2~11^2~28 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=acdd5985364f8dc511a0762fab2e683f29d9d692;p=pandora-kernel.git sctp: Allow struct sctp_event_subscribe to grow without breaking binaries 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 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 Acked-by: Vlad Yasevich Signed-off-by: David S. Miller --- diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 06b42b7f5a02..92ba71dfe080 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))