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authorThomas Graf <tgraf@infradead.org>2012-04-03 22:17:53 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-04-27 09:51:18 -0700
commit3109ea06da8538ee3ded3489b26065a3be32f360 (patch)
treedd6bb6d0624a0c9c93e43980ab6e9077137941f9
parent8d2228dd95c656e5fc9af2e8776f9c95e269806f (diff)
sctp: Allow struct sctp_event_subscribe to grow without breaking binaries
[ Upstream commit acdd5985364f8dc511a0762fab2e683f29d9d692 ] 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@suug.ch> Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/sctp/socket.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index fa9b5c7739a8..4434853a9fe7 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4009,9 +4009,10 @@ 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))