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openSUSE:Step:15
libssh2_org.13039
libssh2_org-CVE-2019-17498.patch
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File libssh2_org-CVE-2019-17498.patch of Package libssh2_org.13039
From dedcbd106f8e52d5586b0205bc7677e4c9868f9c Mon Sep 17 00:00:00 2001 From: Will Cosgrove <will@panic.com> 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. --- src/packet.c | 68 ++++++++++++++++++++++------------------------------ 1 file changed, 29 insertions(+), 39 deletions(-) Index: libssh2-1.8.0/src/packet.c =================================================================== --- libssh2-1.8.0.orig/src/packet.c +++ libssh2-1.8.0/src/packet.c @@ -416,8 +416,8 @@ _libssh2_packet_add(LIBSSH2_SESSION * se 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; @@ -469,32 +469,23 @@ _libssh2_packet_add(LIBSSH2_SESSION * se 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 */ + + _libssh2_get_u32(&buf, &reason); + _libssh2_get_string(&buf, &message, &message_len); + _libssh2_get_string(&buf, &language, &language_len); - if(datalen >= 9) { - message_len = _libssh2_ntohu32(data + 5); - - 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); @@ -534,23 +525,24 @@ _libssh2_packet_add(LIBSSH2_SESSION * se int always_display= data[1]; if(datalen >= 6) { - message_len = _libssh2_ntohu32(data + 2); + struct string_buf buf; + buf.data = (unsigned char *)data; + buf.dataptr = buf.data; + buf.len = datalen; + buf.dataptr += 2; /* advance past type & always display */ - 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; - } + _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 @@ -573,7 +565,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * se 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, Index: libssh2-1.8.0/src/misc.c =================================================================== --- libssh2-1.8.0.orig/src/misc.c +++ libssh2-1.8.0/src/misc.c @@ -643,3 +643,44 @@ void *_libssh2_calloc(LIBSSH2_SESSION* s } return p; } + +/* Given the current location in buf, _libssh2_check_length ensures + callers can read the next len number of bytes out of the buffer + before reading the buffer content */ + +int _libssh2_check_length(struct string_buf *buf, size_t len) +{ + unsigned char *endp = &buf->data[buf->len]; + size_t left = endp - buf->dataptr; + return ((len <= left) && (left <= buf->len)); +} + +int _libssh2_get_u32(struct string_buf *buf, uint32_t *out) +{ + if(!_libssh2_check_length(buf, 4)) { + return -1; + } + + *out = _libssh2_ntohu32(buf->dataptr); + buf->dataptr += 4; + return 0; +} + +int _libssh2_get_string(struct string_buf *buf, unsigned char **outbuf, + size_t *outlen) +{ + uint32_t data_len; + if(_libssh2_get_u32(buf, &data_len) != 0) { + return -1; + } + if(!_libssh2_check_length(buf, data_len)) { + return -1; + } + *outbuf = buf->dataptr; + buf->dataptr += data_len; + + if(outlen) + *outlen = (size_t)data_len; + + return 0; +} Index: libssh2-1.8.0/src/misc.h =================================================================== --- libssh2-1.8.0.orig/src/misc.h +++ libssh2-1.8.0/src/misc.h @@ -49,6 +49,12 @@ struct list_node { struct list_head *head; }; +struct string_buf { + unsigned char *data; + unsigned char *dataptr; + size_t len; +}; + int _libssh2_error_flags(LIBSSH2_SESSION* session, int errcode, const char* errmsg, int errflags); int _libssh2_error(LIBSSH2_SESSION* session, int errcode, const char* errmsg); @@ -80,6 +86,11 @@ void _libssh2_store_u32(unsigned char ** void _libssh2_store_str(unsigned char **buf, const char *str, size_t len); void *_libssh2_calloc(LIBSSH2_SESSION* session, size_t size); +int _libssh2_get_u32(struct string_buf *buf, uint32_t *out); +int _libssh2_get_string(struct string_buf *buf, unsigned char **outbuf, + size_t *outlen); +int _libssh2_check_length(struct string_buf *buf, size_t requested_len); + #if defined(LIBSSH2_WIN32) && !defined(__MINGW32__) && !defined(__CYGWIN__) /* provide a private one */ #undef HAVE_GETTIMEOFDAY
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