From: Fabrice Fontaine Date: Sat, 29 Feb 2020 11:31:32 +0000 (+0100) Subject: package/libssh2: fix CVE-2019-17498 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8d76402ee113bd6d47b0d13162f2a753f98e37d5;p=buildroot.git package/libssh2: fix CVE-2019-17498 In libssh2 v1.9.0 and earlier versions, the SSH_MSG_DISCONNECT logic in packet.c has an integer overflow in a bounds check, enabling an attacker to specify an arbitrary (out-of-bounds) offset for a subsequent memory read. A crafted SSH server may be able to disclose sensitive information or cause a denial of service condition on the client system when a user connects to the server. Signed-off-by: Fabrice Fontaine Signed-off-by: Yann E. MORIN --- diff --git a/package/libssh2/0003-packet-c-improve-message-parsing.patch b/package/libssh2/0003-packet-c-improve-message-parsing.patch new file mode 100644 index 0000000000..2b73520021 --- /dev/null +++ b/package/libssh2/0003-packet-c-improve-message-parsing.patch @@ -0,0 +1,127 @@ +From dedcbd106f8e52d5586b0205bc7677e4c9868f9c Mon Sep 17 00:00:00 2001 +From: Will Cosgrove +Date: Fri, 30 Aug 2019 09:57:38 -0700 +Subject: [PATCH] packet.c: improve message parsing (#402) + +* packet.c: improve parsing of packets + +file: packet.c + +notes: +Use _libssh2_get_string API in SSH_MSG_DEBUG/SSH_MSG_DISCONNECT. Additional uint32 bounds check in SSH_MSG_GLOBAL_REQUEST. +[Retrieved from: +https://github.com/libssh2/libssh2/commit/dedcbd106f8e52d5586b0205bc7677e4c9868f9c] +Signed-off-by: Fabrice Fontaine +--- + src/packet.c | 68 ++++++++++++++++++++++------------------------------ + 1 file changed, 29 insertions(+), 39 deletions(-) + +diff --git a/src/packet.c b/src/packet.c +index 38ab6294..2e01bfc5 100644 +--- a/src/packet.c ++++ b/src/packet.c +@@ -419,8 +419,8 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, + size_t datalen, int macstate) + { + int rc = 0; +- char *message = NULL; +- char *language = NULL; ++ unsigned char *message = NULL; ++ unsigned char *language = NULL; + size_t message_len = 0; + size_t language_len = 0; + LIBSSH2_CHANNEL *channelp = NULL; +@@ -472,33 +472,23 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, + + case SSH_MSG_DISCONNECT: + if(datalen >= 5) { +- size_t reason = _libssh2_ntohu32(data + 1); ++ uint32_t reason = 0; ++ struct string_buf buf; ++ buf.data = (unsigned char *)data; ++ buf.dataptr = buf.data; ++ buf.len = datalen; ++ buf.dataptr++; /* advance past type */ + +- if(datalen >= 9) { +- message_len = _libssh2_ntohu32(data + 5); ++ _libssh2_get_u32(&buf, &reason); ++ _libssh2_get_string(&buf, &message, &message_len); ++ _libssh2_get_string(&buf, &language, &language_len); + +- if(message_len < datalen-13) { +- /* 9 = packet_type(1) + reason(4) + message_len(4) */ +- message = (char *) data + 9; +- +- language_len = +- _libssh2_ntohu32(data + 9 + message_len); +- language = (char *) data + 9 + message_len + 4; +- +- if(language_len > (datalen-13-message_len)) { +- /* bad input, clear info */ +- language = message = NULL; +- language_len = message_len = 0; +- } +- } +- else +- /* bad size, clear it */ +- message_len = 0; +- } + if(session->ssh_msg_disconnect) { +- LIBSSH2_DISCONNECT(session, reason, message, +- message_len, language, language_len); ++ LIBSSH2_DISCONNECT(session, reason, (const char *)message, ++ message_len, (const char *)language, ++ language_len); + } ++ + _libssh2_debug(session, LIBSSH2_TRACE_TRANS, + "Disconnect(%d): %s(%s)", reason, + message, language); +@@ -539,24 +529,24 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, + int always_display = data[1]; + + if(datalen >= 6) { +- message_len = _libssh2_ntohu32(data + 2); +- +- if(message_len <= (datalen - 10)) { +- /* 6 = packet_type(1) + display(1) + message_len(4) */ +- message = (char *) data + 6; +- language_len = _libssh2_ntohu32(data + 6 + +- message_len); +- +- if(language_len <= (datalen - 10 - message_len)) +- language = (char *) data + 10 + message_len; +- } ++ struct string_buf buf; ++ buf.data = (unsigned char *)data; ++ buf.dataptr = buf.data; ++ buf.len = datalen; ++ buf.dataptr += 2; /* advance past type & always display */ ++ ++ _libssh2_get_string(&buf, &message, &message_len); ++ _libssh2_get_string(&buf, &language, &language_len); + } + + if(session->ssh_msg_debug) { +- LIBSSH2_DEBUG(session, always_display, message, +- message_len, language, language_len); ++ LIBSSH2_DEBUG(session, always_display, ++ (const char *)message, ++ message_len, (const char *)language, ++ language_len); + } + } ++ + /* + * _libssh2_debug will actually truncate this for us so + * that it's not an inordinate about of data +@@ -579,7 +569,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, + uint32_t len = 0; + unsigned char want_reply = 0; + len = _libssh2_ntohu32(data + 1); +- if(datalen >= (6 + len)) { ++ if((len <= (UINT_MAX - 6)) && (datalen >= (6 + len))) { + want_reply = data[5 + len]; + _libssh2_debug(session, + LIBSSH2_TRACE_CONN, diff --git a/package/libssh2/libssh2.mk b/package/libssh2/libssh2.mk index bd8517dac4..3819c1aa31 100644 --- a/package/libssh2/libssh2.mk +++ b/package/libssh2/libssh2.mk @@ -11,6 +11,9 @@ LIBSSH2_LICENSE_FILES = COPYING LIBSSH2_INSTALL_STAGING = YES LIBSSH2_CONF_OPTS = --disable-examples-build +# 0003-packet-c-improve-message-parsing.patch +LIBSSH2_IGNORE_CVES += CVE-2019-17498 + # building from a git clone LIBSSH2_AUTORECONF = YES