From 662aa4f1d168b32335a4dc40782e816329afcac0 Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Tue, 14 Apr 2020 18:36:12 +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 | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c index 2a15b16a..019b637a 100644 --- a/slirp/src/tcp_subr.c +++ b/slirp/src/tcp_subr.c @@ -696,7 +696,7 @@ int 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; @@ -732,7 +732,7 @@ int tcp_emu(struct socket *so, struct mbuf *m) m->m_len = bptr - m->m_data; /* Adjust length */ m->m_len += - snprintf(bptr, m->m_size - 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 : ""); @@ -759,7 +759,8 @@ int tcp_emu(struct socket *so, struct mbuf *m) (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; + snprintf(m->m_data, M_ROOM(m), + "%d", ntohs(so->so_fport)) + 1; return 1; case EMU_IRC: -- 2.23.0