https://github.com/libssh2/libssh2/commit/2dae3024897e1898d389835151f4e9606227721d https://bugs.gentoo.org/977961#c9 --- a/src/sftp.c 2024-10-16 10:03:21.000000000 +0200 +++ b/src/sftp.c 2026-07-07 00:53:47.620941153 +0200 @@ -3795,15 +3795,19 @@ { LIBSSH2_CHANNEL *channel = sftp->channel; LIBSSH2_SESSION *session = channel->session; - size_t data_len = 0, link_len; + size_t data_len = 0, lk_len; /* 13 = packet_len(4) + packet_type(1) + request_id(4) + path_len(4) */ ssize_t packet_len = path_len + 13 + ((link_type == LIBSSH2_SFTP_SYMLINK) ? (4 + target_len) : 0); unsigned char *s, *data = NULL; + struct string_buf buf; static const unsigned char link_responses[2] = { SSH_FXP_NAME, SSH_FXP_STATUS }; int retcode; + unsigned char packet_type; + uint32_t tmp_u32; + unsigned char *lk_target; if(sftp->symlink_state == libssh2_NB_state_idle) { sftp->last_errno = LIBSSH2_FX_OK; @@ -3891,8 +3895,25 @@ sftp->symlink_state = libssh2_NB_state_idle; - if(data[0] == SSH_FXP_STATUS) { - retcode = _libssh2_ntohu32(data + 5); + buf.data = data; + buf.dataptr = buf.data; + buf.len = data_len; + + if(_libssh2_get_byte(&buf, &packet_type)) { + LIBSSH2_FREE(session, data); + return _libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, + "SFTP Protocol Error (type)"); + } + + if(packet_type == SSH_FXP_STATUS) { + if(_libssh2_get_u32(&buf, &tmp_u32)) { + LIBSSH2_FREE(session, data); + return _libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, + "SFTP Protocol Error (code)"); + } + + retcode = (int)tmp_u32; + LIBSSH2_FREE(session, data); if(retcode == LIBSSH2_FX_OK) return LIBSSH2_ERROR_NONE; @@ -3903,30 +3924,37 @@ } } - if(_libssh2_ntohu32(data + 5) < 1) { + /* advance past id */ + if(_libssh2_get_u32(&buf, &tmp_u32)) { LIBSSH2_FREE(session, data); return _libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, - "Invalid READLINK/REALPATH response, " - "no name entries"); + "SFTP Protocol Error (id)"); } - if(data_len < 13) { - if(data_len > 0) { - LIBSSH2_FREE(session, data); - } + /* look for at least one link */ + if(_libssh2_get_u32(&buf, &tmp_u32) || tmp_u32 < 1) { + LIBSSH2_FREE(session, data); return _libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, - "SFTP stat packet too short"); + "Invalid READLINK/REALPATH response, " + "no name entries"); } - /* this reads a u32 and stores it into a signed 32bit value */ - link_len = _libssh2_ntohu32(data + 9); - if(link_len < target_len) { - memcpy(target, data + 13, link_len); - target[link_len] = 0; - retcode = (int)link_len; + if(_libssh2_get_string(&buf, &lk_target, &lk_len) == LIBSSH2_ERROR_NONE) { + if(lk_len < target_len) { + memcpy(target, lk_target, lk_len); + target[lk_len] = '\0'; + retcode = (int)lk_len; + } + else { + retcode = LIBSSH2_ERROR_BUFFER_TOO_SMALL; + } } - else - retcode = LIBSSH2_ERROR_BUFFER_TOO_SMALL; + else { + LIBSSH2_FREE(session, data); + return _libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, + "SFTP Protocol Error (filename)"); + } + LIBSSH2_FREE(session, data); return retcode;