From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>,
Neil Horman <nhorman@tuxdriver.com>,
linux-sctp@vger.kernel.org, netdev@vger.kernel.org,
vuln@secunia.com
Subject: Re: [PATCH net] sctp: walk the list of asoc safely
Date: Fri, 1 Feb 2019 15:43:59 +0100 [thread overview]
Message-ID: <20190201144359.GA9864@kroah.com> (raw)
In-Reply-To: <20190201142037.GC10521@localhost.localdomain>
On Fri, Feb 01, 2019 at 12:20:37PM -0200, Marcelo Ricardo Leitner wrote:
> 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@secunia.com>
> > Tested-by: Secunia Research <vuln@secunia.com>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > 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.
What about when the SCTP_ABORT flag is set with SCTP_SENDALL at the same
time?
:(
next prev parent reply other threads:[~2019-02-01 14:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-01 14:15 [PATCH net] sctp: walk the list of asoc safely Greg Kroah-Hartman
2019-02-01 14:20 ` Marcelo Ricardo Leitner
2019-02-01 14:43 ` Greg Kroah-Hartman [this message]
2019-02-01 14:58 ` Marcelo Ricardo Leitner
2019-02-01 15:55 ` Neil Horman
2019-02-01 19:04 ` David Miller
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