From 3f9fbb23959f82de389fa43848bb28cd2b80a4bb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <philmd@redhat.com>
Date: Fri, 6 Sep 2019 14:00:34 +0200
Subject: [PATCH 1/4] Using ip_deq after m_free might read pointers from an
allocation reuse.
MIME-Version: 1.0
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RH-Author: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: <20190906140034.19722-2-philmd@redhat.com>
Patchwork-id: 90306
O-Subject: [RHEL-7.7 qemu-kvm-ma + RHEL-7.7 qemu-kvm-rhev + RHEL-8.1.0 qemu-kvm PATCH 1/1] Using ip_deq after m_free might read pointers from an allocation reuse.
Bugzilla: 1749723
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
This would be difficult to exploit, but that is still related with
CVE-2019-14378 which generates fragmented IP packets that would trigger this
issue and at least produce a DoS.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
(cherry picked from libslirp commit c59279437eda91841b9d26079c70b8a540d41204)
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
slirp/ip_input.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/slirp/ip_input.c b/slirp/ip_input.c
index 07d8808..7cf0133 100644
--- a/slirp/ip_input.c
+++ b/slirp/ip_input.c
@@ -300,6 +300,7 @@ ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
*/
while (q != (struct ipasfrag*)&fp->frag_link &&
ip->ip_off + ip->ip_len > q->ipf_off) {
+ struct ipasfrag *prev;
i = (ip->ip_off + ip->ip_len) - q->ipf_off;
if (i < q->ipf_len) {
q->ipf_len -= i;
@@ -307,9 +308,10 @@ ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
m_adj(dtom(slirp, q), i);
break;
}
+ prev = q;
q = q->ipf_next;
- m_free(dtom(slirp, q->ipf_prev));
- ip_deq(q->ipf_prev);
+ ip_deq(prev);
+ m_free(dtom(slirp, prev));
}
insert:
--
1.8.3.1