From 66e2f47a01ffcaafe11acae0a191efd1805f86c6 Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Wed, 11 Mar 2020 18:27:22 +0800 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: default avatarPrasad J Pandit Signed-off-by: Samuel Thibault's avatarSamuel Thibault Message-Id: <20200109094228.79764-3-ppandit@redhat.com> --- slirp/src/tcp_subr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c index 2053b11b..e898fd03 100644 --- a/slirp/src/tcp_subr.c +++ b/slirp/src/tcp_subr.c @@ -707,7 +707,7 @@ tcp_emu(struct socket *so, struct mbuf *m) 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; @@ -740,7 +740,7 @@ tcp_emu(struct socket *so, struct mbuf *m) 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:""); @@ -766,8 +766,8 @@ tcp_emu(struct socket *so, struct mbuf *m) 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: -- 2.21.1 (Apple Git-122.3)