| From 0b03959b72036afce151783720d9e54988cf76ef Mon Sep 17 00:00:00 2001 |
| From: Changqing Li <changqing.li@windriver.com> |
| Date: Thu, 27 Feb 2020 12:15:04 +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 <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> |
| |
| CVE: CVE-2020-7039 |
| Upstream-Status: Backport |
| [https://gitlab.freedesktop.org/slirp/libslirp/commit/ce131029d6d4a405cb7d3ac6716d03e58fb4a5d9] |
| |
| Signed-off-by: Changqing Li <changqing.li@windriver.com> |
| --- |
| slirp/src/tcp_subr.c | 11 ++++++----- |
| 1 file changed, 6 insertions(+), 5 deletions(-) |
| |
| diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c |
| index e8ed4ef..3a4a8ee 100644 |
| --- a/slirp/src/tcp_subr.c |
| +++ b/slirp/src/tcp_subr.c |
| @@ -777,7 +777,8 @@ 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, |
| @@ -787,8 +788,8 @@ 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, |
| @@ -798,8 +799,8 @@ 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); |
| } |
| -- |
| 2.7.4 |
| |