[PATCH 4.16 26/55] sctp: remove sctp_chunk_put from fail_mark err path in sctp_ulpevent_make_rcvmsg

Greg Kroah-Hartman
2018-05-18T08:15:22Z

From: Xin Long <lucien.xin@gmail.com>

[ Upstream commit 6910e25de2257e2c82c7a2d126e3463cd8e50810 ]

In Commit 1f45f78f8e51 ("sctp: allow GSO frags to access the chunk too"),
it held the chunk in sctp_ulpevent_make_rcvmsg to access it safely later
in recvmsg. However, it also added sctp_chunk_put in fail_mark err path,
which is only triggered before holding the chunk.

syzbot reported a use-after-free crash happened on this err path, where
it shouldn't call sctp_chunk_put.

This patch simply removes this call.

Fixes: 1f45f78f8e51 ("sctp: allow GSO frags to access the chunk too")
Reported-by: syzbot+141d898c5f24489db4aa@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sctp/ulpevent.c | 1 -
1 file changed, 1 deletion(-)

--- a/net/sctp/ulpevent.c
+++ b/net/sctp/ulpevent.c
@@ -715,7 +715,6 @@ struct sctp_ulpevent *sctp_ulpevent_make
return event;

fail_mark:
- sctp_chunk_put(chunk);
kfree_skb(skb);
fail:
return NULL;