From 2655fffed7a9e765bcb4701dd876e9dab975f289 Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Wed, 8 Jan 2020 00:58:48 +0100
Subject: [PATCH] tcp_emu: Fix oob access
The main loop only checks for one available byte, while we sometimes
need two bytes.
2.24.1
From 82ebe9c370a0e2970fb5695aa19aa5214a6a1c80 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 9 Jan 2020 15:12:28 +0530
Subject: [PATCH] slirp: use correct size while emulating commands
While emulating services in tcp_emu(), it uses 'mbuf' size
'm->m_size' to write commands via snprintf(3). Use M_FREEROOM(m)
size to avoid possible OOB access.
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Message-Id: <20200109094228.79764-3-ppandit@redhat.com>
2.24.1
From ce131029d6d4a405cb7d3ac6716d03e58fb4a5d9 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 9 Jan 2020 15:12:27 +0530
Subject: [PATCH] slirp: use correct size while emulating IRC commands
While emulating IRC DCC commands, tcp_emu() uses 'mbuf' size
'm->m_size' to write DCC commands via snprintf(3). This may
lead to OOB write access, because 'bptr' points somewhere in
the middle of 'mbuf' buffer, not at the start. Use M_FREEROOM(m)
size to avoid OOB access.
Reported-by: Vishnu Dev TJ <vishnudevtj@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Message-Id: <20200109094228.79764-2-ppandit@redhat.com>
---
CHANGELOG.md | 1 +
src/tcp_subr.c | 7 +++++++
2 files changed, 8 insertions(+)
diff -up ./slirp4netns-21fdece2737dc24ffa3f01a341b8a6854f8b13b4/vendor/libslirp/src/tcp_subr.c.CVE-2020-7039 ./slirp4netns-21fdece2737dc24ffa3f01a341b8a6854f8b13b4/vendor/libslirp/src/tcp_subr.c
--- slirp4netns-21fdece2737dc24ffa3f01a341b8a6854f8b13b4/vendor/libslirp/src/tcp_subr.c.CVE-2020-7039 2020-01-16 11:14:05.423941479 +0100
+++ slirp4netns-21fdece2737dc24ffa3f01a341b8a6854f8b13b4/vendor/libslirp/src/tcp_subr.c 2020-01-16 11:14:05.425941502 +0100
@@ -692,7 +692,7 @@ int tcp_emu(struct socket *so, struct mb
n4 = (laddr & 0xff);
m->m_len = bptr - m->m_data; /* Adjust length */
- m->m_len += snprintf(bptr, m->m_size - m->m_len,
+ m->m_len += snprintf(bptr, M_FREEROOM(m),
"ORT %d,%d,%d,%d,%d,%d\r\n%s", n1, n2, n3, n4,
n5, n6, x == 7 ? buff : "");
return 1;
@@ -727,8 +727,7 @@ int tcp_emu(struct socket *so, struct mb
n4 = (laddr & 0xff);
m->m_len = bptr - m->m_data; /* Adjust length */
- m->m_len +=
- snprintf(bptr, m->m_size - m->m_len,
+ m->m_len += snprintf(bptr, M_FREEROOM(m),
"27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
n1, n2, n3, n4, n5, n6, x == 7 ? buff : "");
@@ -754,8 +753,8 @@ int tcp_emu(struct socket *so, struct mb
if (m->m_data[m->m_len - 1] == '\0' && lport != 0 &&
(so = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,
htons(lport), SS_FACCEPTONCE)) != NULL)
- m->m_len =
- snprintf(m->m_data, m->m_size, "%d", ntohs(so->so_fport)) + 1;
+ m->m_len = snprintf(m->m_data, M_ROOM(m),
+ "%d", ntohs(so->so_fport)) + 1;
return 1;
case EMU_IRC:
@@ -774,7 +773,8 @@ int tcp_emu(struct socket *so, struct mb
return 1;
}
m->m_len = bptr - m->m_data; /* Adjust length */
- m->m_len += snprintf(bptr, m->m_size, "DCC CHAT chat %lu %u%c\n",
+ m->m_len += snprintf(bptr, M_FREEROOM(m),
+ "DCC CHAT chat %lu %u%c\n",
(unsigned long)ntohl(so->so_faddr.s_addr),
ntohs(so->so_fport), 1);
} else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport,
@@ -784,8 +784,8 @@ int tcp_emu(struct socket *so, struct mb
return 1;
}
m->m_len = bptr - m->m_data; /* Adjust length */
- m->m_len +=
- snprintf(bptr, m->m_size, "DCC SEND %s %lu %u %u%c\n", buff,
+ m->m_len += snprintf(bptr, M_FREEROOM(m),
+ "DCC SEND %s %lu %u %u%c\n", buff,
(unsigned long)ntohl(so->so_faddr.s_addr),
ntohs(so->so_fport), n1, 1);
} else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport,
@@ -795,8 +795,8 @@ int tcp_emu(struct socket *so, struct mb
return 1;
}
m->m_len = bptr - m->m_data; /* Adjust length */
- m->m_len +=
- snprintf(bptr, m->m_size, "DCC MOVE %s %lu %u %u%c\n", buff,
+ m->m_len += snprintf(bptr, M_FREEROOM(m),
+ "DCC MOVE %s %lu %u %u%c\n", buff,
(unsigned long)ntohl(so->so_faddr.s_addr),
ntohs(so->so_fport), n1, 1);
}
@@ -882,6 +882,9 @@ int tcp_emu(struct socket *so, struct mb
break;
case 5:
+ if (bptr == m->m_data + m->m_len - 1)
+ return 1; /* We need two bytes */
+
/*
* The difference between versions 1.0 and
* 2.0 is here. For future versions of
@@ -897,6 +900,10 @@ int tcp_emu(struct socket *so, struct mb
/* This is the field containing the port
* number that RA-player is listening to.
*/
+
+ if (bptr == m->m_data + m->m_len - 1)
+ return 1; /* We need two bytes */
+
lport = (((uint8_t *)bptr)[0] << 8) + ((uint8_t *)bptr)[1];
if (lport < 6970)
lport += 256; /* don't know why */