From 882149fd8401f8ff667ea384bb68008354fd110f Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Wed, 11 Mar 2020 18:19:36 +0800 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: default avatarVishnu Dev TJ Signed-off-by: default avatarPrasad J Pandit Reviewed-by: Samuel Thibault's avatarSamuel Thibault Message-Id: <20200109094228.79764-2-ppandit@redhat.com> --- slirp/src/tcp_subr.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c index 4608942f..2053b11b 100644 --- a/slirp/src/tcp_subr.c +++ b/slirp/src/tcp_subr.c @@ -786,7 +786,7 @@ tcp_emu(struct socket *so, struct mbuf *m) return 1; } 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), "DCC CHAT chat %lu %u%c\n", (unsigned long)ntohl(so->so_faddr.s_addr), ntohs(so->so_fport), 1); @@ -797,7 +797,7 @@ tcp_emu(struct socket *so, struct mbuf *m) return 1; } 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), "DCC SEND %s %lu %u %u%c\n", buff, (unsigned long)ntohl(so->so_faddr.s_addr), ntohs(so->so_fport), n1, 1); @@ -808,7 +808,7 @@ tcp_emu(struct socket *so, struct mbuf *m) return 1; } 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), "DCC MOVE %s %lu %u %u%c\n", buff, (unsigned long)ntohl(so->so_faddr.s_addr), ntohs(so->so_fport), n1, 1); -- 2.21.1 (Apple Git-122.3)