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46 lines
1.5 KiB
46 lines
1.5 KiB
From c59279437eda91841b9d26079c70b8a540d41204 Mon Sep 17 00:00:00 2001
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From: Samuel Thibault <samuel.thibault@ens-lyon.org>
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Date: Mon, 26 Aug 2019 00:55:03 +0200
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Subject: [PATCH] ip_reass: Fix use after free
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Using ip_deq after m_free might read pointers from an allocation reuse.
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This would be difficult to exploit, but that is still related with
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CVE-2019-14378 which generates fragmented IP packets that would trigger this
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issue and at least produce a DoS.
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Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
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---
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Taken from https://gitlab.freedesktop.org/slirp/libslirp/commit/c5927943
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slirp/src/ip_input.c | 6 ++++--
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1 file changed, 4 insertions(+), 2 deletions(-)
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diff --git a/slirp/src/ip_input.c b/slirp/src/ip_input.c
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index 7364ce0..aa514ae 100644
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--- a/slirp/src/ip_input.c
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+++ b/slirp/src/ip_input.c
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@@ -292,6 +292,7 @@ static struct ip *ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
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*/
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while (q != (struct ipasfrag *)&fp->frag_link &&
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ip->ip_off + ip->ip_len > q->ipf_off) {
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+ struct ipasfrag *prev;
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i = (ip->ip_off + ip->ip_len) - q->ipf_off;
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if (i < q->ipf_len) {
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q->ipf_len -= i;
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@@ -299,9 +300,10 @@ static struct ip *ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
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m_adj(dtom(slirp, q), i);
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break;
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}
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+ prev = q;
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q = q->ipf_next;
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- m_free(dtom(slirp, q->ipf_prev));
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- ip_deq(q->ipf_prev);
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+ ip_deq(prev);
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+ m_free(dtom(slirp, prev));
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}
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insert:
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--
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2.22.0
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