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From 4fc0d23e8f6d795c679623d2ed2cbe6a7a17b9c7 Mon Sep 17 00:00:00 2001
From: Li Zhou <li.zhou@windriver.com>
Date: Tue, 10 Sep 2019 20:02:15 -0700
Subject: [PATCH] ip_reass: Fix use after free
Using ip_deq after m_free might read pointers from an allocation reuse.
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>
Upstream-Status: Backport
CVE: CVE-2019-15890
Signed-off-by: Li Zhou <li.zhou@windriver.com>
---
slirp/src/ip_input.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/slirp/src/ip_input.c b/slirp/src/ip_input.c
index 8c75d914..c07d7d40 100644
--- a/slirp/src/ip_input.c
+++ b/slirp/src/ip_input.c
@@ -292,6 +292,7 @@ static struct ip *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;
@@ -299,9 +300,10 @@ static struct ip *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:
--
2.23.0
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