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authorThomas Graf <tgraf@infradead.org>2012-04-03 22:17:53 +0000
committerDavid S. Miller <davem@davemloft.net>2012-04-04 18:05:02 -0400
commitacdd5985364f8dc511a0762fab2e683f29d9d692 (patch)
treee06a7741371bb6905158fc70a3f05121e07f0306 /net
parentd96fc659aeb27686cef42d305cfd0c9702f8841c (diff)
downloadlinux-linaro-stable-acdd5985364f8dc511a0762fab2e683f29d9d692.tar.gz
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 <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>
Diffstat (limited to 'net')
-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 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))