From 486e74dd9b8515f478698fee494086b339015d51 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <philmd@redhat.com>

Date: Wed, 31 Jul 2019 18:45:29 +0100

Subject: [PATCH 14/14] Fix heap overflow in ip_reass on big packet input

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RH-Author: Philippe Mathieu-Daudé <philmd@redhat.com>

Message-id: <20190731184529.21905-2-philmd@redhat.com>

Patchwork-id: 89820

O-Subject: [RHEL-8.1.0 qemu-kvm PATCH 1/1] Fix heap overflow in ip_reass on big packet input

Bugzilla: 1734751

RH-Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Thomas Huth <thuth@redhat.com>

From: Samuel Thibault <samuel.thibault@ens-lyon.org>

When the first fragment does not fit in the preallocated buffer, q will

already be pointing to the ext buffer, so we mustn't try to update it.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

(cherry picked from libslirp commit 126c04acbabd7ad32c2b018fe10dfac2a3bc1210)

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 slirp/ip_input.c | 4 +++-

 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/slirp/ip_input.c b/slirp/ip_input.c

index 348e1dc..07d8808 100644

--- a/slirp/ip_input.c

+++ b/slirp/ip_input.c

@@ -334,6 +334,8 @@ insert:

     q = fp->frag_link.next;

 	m = dtom(slirp, q);

+	int was_ext = m->m_flags & M_EXT;

+

 	q = (struct ipasfrag *) q->ipf_next;

 	while (q != (struct ipasfrag*)&fp->frag_link) {

 	  struct mbuf *t = dtom(slirp, q);

@@ -356,7 +358,7 @@ insert:

 	 * the old buffer (in the mbuf), so we must point ip

 	 * into the new buffer.

 	 */

-	if (m->m_flags & M_EXT) {

+	if (!was_ext && m->m_flags & M_EXT) {

 	  int delta = (char *)q - m->m_dat;

 	  q = (struct ipasfrag *)(m->m_ext + delta);

 	}

-- 

1.8.3.1