From 0e4e9825e637a15707a910539d71fe65e7e12d7b Mon Sep 17 00:00:00 2001
From: Kamil Dudka <kdudka@redhat.com>
Date: Tue, 19 Mar 2019 13:45:22 +0100
Subject: [PATCH] Resolves: CVE-2019-3862 - fix out-of-bounds memory comparison

... with specially crafted message channel request

Upstream-Patch: https://libssh2.org/1.8.0-CVE/CVE-2019-3862.patch
---
 src/packet.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/packet.c b/src/packet.c
index aa10633..c950b5d 100644
--- a/src/packet.c
+++ b/src/packet.c
@@ -775,8 +775,8 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
                 uint32_t len = _libssh2_ntohu32(data + 5);
                 unsigned char want_reply = 1;
 
-                if(len < (datalen - 10))
-                    want_reply = data[9 + len];
+                if((len + 9) < datalen)
+                    want_reply = data[len + 9];
 
                 _libssh2_debug(session,
                                LIBSSH2_TRACE_CONN,
@@ -784,6 +784,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
                                channel, len, data + 9, want_reply);
 
                 if (len == sizeof("exit-status") - 1
+                    && (sizeof("exit-status") - 1 + 9) <= datalen
                     && !memcmp("exit-status", data + 9,
                                sizeof("exit-status") - 1)) {
 
@@ -792,7 +793,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
                         channelp =
                             _libssh2_channel_locate(session, channel);
 
-                    if (channelp) {
+                    if (channelp && (sizeof("exit-status") + 13) <= datalen) {
                         channelp->exit_status =
                             _libssh2_ntohu32(data + 9 + sizeof("exit-status"));
                         _libssh2_debug(session, LIBSSH2_TRACE_CONN,
@@ -805,13 +806,14 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
 
                 }
                 else if (len == sizeof("exit-signal") - 1
+                         && (sizeof("exit-signal") - 1 + 9) <= datalen
                          && !memcmp("exit-signal", data + 9,
                                     sizeof("exit-signal") - 1)) {
                     /* command terminated due to signal */
                     if(datalen >= 20)
                         channelp = _libssh2_channel_locate(session, channel);
 
-                    if (channelp) {
+                    if (channelp && (sizeof("exit-signal") + 13) <= datalen) {
                         /* set signal name (without SIG prefix) */
                         uint32_t namelen =
                             _libssh2_ntohu32(data + 9 + sizeof("exit-signal"));
@@ -827,9 +829,9 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
                         if (!channelp->exit_signal)
                             rc = _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
                                                 "memory for signal name");
-                        else {
+                        else if ((sizeof("exit-signal") + 13 + namelen <= datalen)) {
                             memcpy(channelp->exit_signal,
-                                   data + 13 + sizeof("exit_signal"), namelen);
+                                   data + 13 + sizeof("exit-signal"), namelen);
                             channelp->exit_signal[namelen] = '\0';
                             /* TODO: save error message and language tag */
                             _libssh2_debug(session, LIBSSH2_TRACE_CONN,
-- 
2.17.2