Subject: [PATCH 4.19 10/61] sctp: Free cookie before we memdup a new one

From: Greg Kroah-Hartman <[email-masked]>
Date: Thu, 20 Jun 2019 19:57:05 +0200

From: Neil Horman <[email-masked]>

[ Upstream commit ce950f1050cece5e406a5cde723c69bba60e1b26 ]

Based on comments from Xin, even after fixes for our recent syzbot
report of cookie memory leaks, its possible to get a resend of an INIT
chunk which would lead to us leaking cookie memory.

To ensure that we don't leak cookie memory, free any previously
allocated cookie first.

Change notes
v1->v2
update subsystem tag in subject (davem)
repeat kfree check for peer_random and peer_hmacs (xin)

v2->v3
net->sctp
also free peer_chunks

v3->v4
fix subject tags

v4->v5
remove cut line

Signed-off-by: Neil Horman <[email-masked]>
Reported-by: [email-masked]
CC: Marcelo Ricardo Leitner <[email-masked]>
CC: Xin Long <[email-masked]>
CC: "David S. Miller" <[email-masked]>
CC: [email-masked]
Acked-by: Marcelo Ricardo Leitner <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
---
 net/sctp/sm_make_chunk.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -2600,6 +2600,8 @@ do_addr_param:
 	case SCTP_PARAM_STATE_COOKIE:
 		asoc->peer.cookie_len =
 			ntohs(param.p->length) - sizeof(struct sctp_paramhdr);
+		if (asoc->peer.cookie)
+			kfree(asoc->peer.cookie);
 		asoc->peer.cookie = kmemdup(param.cookie->body, asoc->peer.cookie_len, gfp);
 		if (!asoc->peer.cookie)
 			retval = 0;
@@ -2664,6 +2666,8 @@ do_addr_param:
 			goto fall_through;
 
 		/* Save peer's random parameter */
+		if (asoc->peer.peer_random)
+			kfree(asoc->peer.peer_random);
 		asoc->peer.peer_random = kmemdup(param.p,
 					    ntohs(param.p->length), gfp);
 		if (!asoc->peer.peer_random) {
@@ -2677,6 +2681,8 @@ do_addr_param:
 			goto fall_through;
 
 		/* Save peer's HMAC list */
+		if (asoc->peer.peer_hmacs)
+			kfree(asoc->peer.peer_hmacs);
 		asoc->peer.peer_hmacs = kmemdup(param.p,
 					    ntohs(param.p->length), gfp);
 		if (!asoc->peer.peer_hmacs) {
@@ -2692,6 +2698,8 @@ do_addr_param:
 		if (!ep->auth_enable)
 			goto fall_through;
 
+		if (asoc->peer.peer_chunks)
+			kfree(asoc->peer.peer_chunks);
 		asoc->peer.peer_chunks = kmemdup(param.p,
 					    ntohs(param.p->length), gfp);
 		if (!asoc->peer.peer_chunks)