Commit ce131029 authored by Prasad J Pandit's avatar Prasad J Pandit Committed by Samuel Thibault

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 <vishnudevtj@gmail.com>
Signed-off-by: default avatarPrasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Samuel Thibault's avatarSamuel Thibault <samuel.thibault@ens-lyon.org>
Message-Id: <20200109094228.79764-2-ppandit@redhat.com>
parent 3fc6296b
......@@ -763,7 +763,8 @@ int 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, "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,
......@@ -773,8 +774,8 @@ int 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, "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,
......@@ -784,8 +785,8 @@ int 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, "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);
}
......
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