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qemu-patch-raspberry4
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slrip: 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>
(from libslirp.git commit c59279437eda91841b9d26079c70b8a540d41204)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
stable-3.1
Michael Roth 2019-09-24 12:18:07 -05:00
parent 28c1dde9aa
commit 9efdbc0224
1 changed files with 4 additions and 2 deletions
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6
slirp/ip_input.c
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@ -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: