On Fri, Feb 01, 2019 at 03:15:22PM +0100, Greg Kroah-Hartman wrote:
> In sctp_sendmesg(), when walking the list of endpoint associations, the
> association can be dropped from the list, making the list corrupt.
> Properly handle this by using list_for_each_entry_safe()
>
> Fixes: 4910280503f3 ("sctp: add support for snd flag SCTP_SENDALL process in sendmsg")
> Reported-by: Secunia Research <vuln@xxxxxxxxxxx>
> Tested-by: Secunia Research <vuln@xxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index f93c3cf9e567..65d6d04546ae 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -2027,7 +2027,7 @@ static int sctp_sendmsg(struct sock *sk, struct msghdr *msg, size_t msg_len)
> struct sctp_endpoint *ep = sctp_sk(sk)->ep;
> struct sctp_transport *transport = NULL;
> struct sctp_sndrcvinfo _sinfo, *sinfo;
> - struct sctp_association *asoc;
> + struct sctp_association *asoc, *tmp;
> struct sctp_cmsgs cmsgs;
> union sctp_addr *daddr;
> bool new = false;
> @@ -2053,7 +2053,7 @@ static int sctp_sendmsg(struct sock *sk, struct msghdr *msg, size_t msg_len)
Extending the context here by 1 line:
lock_sock(sk);
>
> /* SCTP_SENDALL process */
> if ((sflags & SCTP_SENDALL) && sctp_style(sk, UDP)) {
> - list_for_each_entry(asoc, &ep->asocs, asocs) {
> + list_for_each_entry_safe(asoc, tmp, &ep->asocs, asocs) {
With the socket being locked by here, how can an asoc be removed
while the list is being traversed? The socket lock should be
protecting from it.
> err = sctp_sendmsg_check_sflags(asoc, sflags, msg,
> msg_len);
> if (err == 0)
