[PATCH 4.19 273/313] sctp: walk the list of asoc safely

Greg Kroah-Hartman
2019-02-11T15:36:35Z

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit ba59fb0273076637f0add4311faa990a5eec27c0 ]

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>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sctp/socket.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -2045,7 +2045,7 @@ static int sctp_sendmsg(struct sock *sk,
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;
@@ -2071,7 +2071,7 @@ static int sctp_sendmsg(struct 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) {
err = sctp_sendmsg_check_sflags(asoc, sflags, msg,
msg_len);
if (err == 0)