| From 9a7810c257711ce02627916d886fc1029f7a8190 Mon Sep 17 00:00:00 2001 |
| From: jmaloy <jmaloy@redhat.com> |
| Date: Thu, 13 Feb 2020 15:50:49 +0000 |
| Subject: [PATCH 3/7] tcp_emu: fix unsafe snprintf() usages |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| RH-Author: jmaloy <jmaloy@redhat.com> |
| Message-id: <20200213155049.3936-3-jmaloy@redhat.com> |
| Patchwork-id: 93826 |
| O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH 2/2] tcp_emu: fix unsafe snprintf() usages |
| Bugzilla: 1798994 |
| RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com> |
| RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com> |
| RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com> |
| |
| From: Marc-André Lureau <marcandre.lureau@redhat.com> |
| |
| Various calls to snprintf() assume that snprintf() returns "only" the |
| number of bytes written (excluding terminating NUL). |
| |
| https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.html#tag_16_159_04 |
| |
| "Upon successful completion, the snprintf() function shall return the |
| number of bytes that would be written to s had n been sufficiently |
| large excluding the terminating null byte." |
| |
| Before patch ce131029, if there isn't enough room in "m_data" for the |
| "DCC ..." message, we overflow "m_data". |
| |
| After the patch, if there isn't enough room for the same, we don't |
| overflow "m_data", but we set "m_len" out-of-bounds. The next time an |
| access is bounded by "m_len", we'll have a buffer overflow then. |
| |
| Use slirp_fmt*() to fix potential OOB memory access. |
| |
| Reported-by: Laszlo Ersek <lersek@redhat.com> |
| Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> |
| Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> |
| Message-Id: <20200127092414.169796-7-marcandre.lureau@redhat.com> |
| (cherry picked from libslirp commit 68ccb8021a838066f0951d4b2817eb6b6f10a843) |
| Signed-off-by: Jon Maloy <jmaloy@redhat.com> |
| |
| Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com> |
| |
| slirp/src/tcp_subr.c | 44 +++++++++++++++++++++----------------------- |
| 1 file changed, 21 insertions(+), 23 deletions(-) |
| |
| diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c |
| index 954d1a6..26d4ead 100644 |
| |
| |
| @@ -655,8 +655,7 @@ int tcp_emu(struct socket *so, struct mbuf *m) |
| NTOHS(n1); |
| NTOHS(n2); |
| m_inc(m, snprintf(NULL, 0, "%d,%d\r\n", n1, n2) + 1); |
| - m->m_len = snprintf(m->m_data, M_ROOM(m), "%d,%d\r\n", n1, n2); |
| - assert(m->m_len < M_ROOM(m)); |
| + m->m_len = slirp_fmt(m->m_data, M_ROOM(m), "%d,%d\r\n", n1, n2); |
| } else { |
| *eol = '\r'; |
| } |
| @@ -696,9 +695,9 @@ 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_FREEROOM(m), |
| - "ORT %d,%d,%d,%d,%d,%d\r\n%s", n1, n2, n3, n4, |
| - n5, n6, x == 7 ? buff : ""); |
| + m->m_len += slirp_fmt(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; |
| } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) { |
| /* |
| @@ -731,10 +730,9 @@ 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_FREEROOM(m), |
| - "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s", |
| - n1, n2, n3, n4, n5, n6, x == 7 ? buff : ""); |
| - |
| + m->m_len += slirp_fmt(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 : ""); |
| return 1; |
| } |
| |
| @@ -757,8 +755,8 @@ int 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_ROOM(m), |
| - "%d", ntohs(so->so_fport)) + 1; |
| + m->m_len = slirp_fmt0(m->m_data, M_ROOM(m), |
| + "%d", ntohs(so->so_fport)); |
| return 1; |
| |
| case EMU_IRC: |
| @@ -777,10 +775,10 @@ 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_FREEROOM(m), |
| - "DCC CHAT chat %lu %u%c\n", |
| - (unsigned long)ntohl(so->so_faddr.s_addr), |
| - ntohs(so->so_fport), 1); |
| + m->m_len += slirp_fmt(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, |
| &n1) == 4) { |
| if ((so = tcp_listen(slirp, INADDR_ANY, 0, htonl(laddr), |
| @@ -788,10 +786,10 @@ 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_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); |
| + m->m_len += slirp_fmt(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, |
| &n1) == 4) { |
| if ((so = tcp_listen(slirp, INADDR_ANY, 0, htonl(laddr), |
| @@ -799,10 +797,10 @@ 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_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); |
| + m->m_len += slirp_fmt(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); |
| } |
| return 1; |
| |
| -- |
| 1.8.3.1 |
| |