Change:
<ins> diff -ur openslp-2.0.0.orig/common/slp_buffer.c openslp-2.0.0/common/slp_buffer.c --- openslp-2.0.0.orig/common/slp_buffer.c	2012-12-10 15:31:53.000000000 -0800 +++ openslp-2.0.0/common/slp_buffer.c	2019-11-26 21:54:20.000000000 -0800 @@ -30,6 +30,13 @@ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *-------------------------------------------------------------------------*/ +/* Copyright (c) 2019 VMware, Inc. + * SPDX-License-Identifier: BSD-3-Clause + * This file is provided under the BSD-3-Clause license. + * See COPYING file for more details and other copyrights + * that may apply. + */ + /** Functions for managing SLP message buffers. * * This file provides a higher level abstraction over malloc and free that @@ -153,4 +160,20 @@ xfree(buf); } +/** Report remaining free buffer size in bytes. + * + * Check if buffer is allocated and if so return bytes left in a + * @c SLPBuffer object. + * + * @param[in] buf The SLPBuffer to be freed. + */ +size_t +RemainingBufferSpace(SLPBuffer buf) +{ +   if (buf->allocated == 0) { +      return 0; +   } +   return buf->end - buf->curpos; +} + /*=========================================================================*/ diff -ur openslp-2.0.0.orig/common/slp_buffer.h openslp-2.0.0/common/slp_buffer.h --- openslp-2.0.0.orig/common/slp_buffer.h	2012-11-28 09:07:04.000000000 -0800 +++ openslp-2.0.0/common/slp_buffer.h	2019-11-26 21:54:32.000000000 -0800 @@ -30,6 +30,13 @@ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *-------------------------------------------------------------------------*/ +/* Copyright (c) 2019 VMware, Inc. + * SPDX-License-Identifier: BSD-3-Clause + * This file is provided under the BSD-3-Clause license. + * See COPYING file for more details and other copyrights + * that may apply. + */ + /** Header file that defines SLP message buffer management routines. * * Includes structures, constants and functions that used to handle memory @@ -78,6 +85,8 @@ SLPBuffer SLPBufferListAdd(SLPBuffer * list, SLPBuffer buf); +size_t RemainingBufferSpace(SLPBuffer buf); + /*! @} */ #endif /* SLP_BUFFER_H_INCLUDED */ diff -ur openslp-2.0.0.orig/slpd/slpd_process.c openslp-2.0.0/slpd/slpd_process.c --- openslp-2.0.0.orig/slpd/slpd_process.c	2012-12-12 09:38:54.000000000 -0800 +++ openslp-2.0.0/slpd/slpd_process.c	2019-11-26 21:55:10.000000000 -0800 @@ -30,6 +30,13 @@ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *-------------------------------------------------------------------------*/ +/* Copyright (c) 2019 VMware, Inc. + * SPDX-License-Identifier: BSD-3-Clause + * This file is provided under the BSD-3-Clause license. + * See COPYING file for more details and other copyrights + * that may apply. + */ + /** Processes incoming SLP messages. * * @file       slpd_process.c @@ -514,13 +521,27 @@ { for (i = 0; i < db->urlcount; i++) { -         /* urlentry is the url from the db result */ urlentry = db->urlarray[i]; +         if (urlentry->opaque != NULL) { +            const int64_t newsize = size + urlentry->opaquelen; +            if (urlentry->opaquelen <= 0 || newsize > INT_MAX) +            { +               SLPDLog("Invalid opaquelen %d or sizeo of opaque url is too big, size=%dn", +                       urlentry->opaquelen, size); +               errorcode = SLP_ERROR_PARSE_ERROR; +               goto FINISHED; +            } +            size +=  urlentry->opaquelen; +         } +         else +         { +            /* urlentry is the url from the db result */ +            size += urlentry->urllen + 6; /*  1 byte for reserved  */ +                                          /*  2 bytes for lifetime */ +                                          /*  2 bytes for urllen   */ +                                          /*  1 byte for authcount */ +          } -         size += urlentry->urllen + 6; /*  1 byte for reserved  */ -                                       /*  2 bytes for lifetime */ -                                       /*  2 bytes for urllen   */ -                                       /*  1 byte for authcount */ #ifdef ENABLE_SLPv2_SECURITY /* make room to include the authblock that was asked for */ if (G_SlpdProperty.securityEnabled @@ -594,7 +615,7 @@ urlentry = db->urlarray[i]; #ifdef ENABLE_SLPv1 -         if (urlentry->opaque == 0) +         if (urlentry->opaque == NULL) { /* url-entry reserved */ *result->curpos++ = 0; @@ -606,8 +627,18 @@ PutUINT16(&result->curpos, urlentry->urllen); /* url-entry url */ -            memcpy(result->curpos, urlentry->url, urlentry->urllen); -            result->curpos += urlentry->urllen; +            if (RemainingBufferSpace(result) >= urlentry->urllen) +            { +               memcpy(result->curpos, urlentry->url, urlentry->urllen); +               result->curpos = result->curpos + urlentry->urllen; +            } +            else +            { +                SLPDLog("Url too big (ask: %d have %" PRId64 "), failing requestn", +                        urlentry->opaquelen, (int64_t) RemainingBufferSpace(result)); +                errorcode = SLP_ERROR_PARSE_ERROR; +                goto FINISHED; +            } /* url-entry auths */ *result->curpos++ = 0; @@ -621,8 +652,18 @@ /* TRICKY: Fix up the lifetime. */ TO_UINT16(urlentry->opaque + 1, urlentry->lifetime); -            memcpy(result->curpos, urlentry->opaque, urlentry->opaquelen); -            result->curpos += urlentry->opaquelen; +            if (RemainingBufferSpace(result) >= urlentry->opaquelen) +            { +               memcpy(result->curpos, urlentry->opaque, urlentry->opaquelen); +               result->curpos = result->curpos + urlentry->opaquelen; +             } +             else +             { +               SLPDLog("Opaque Url too big (ask: %d have %" PRId64 "), failing requestn", +                       urlentry->opaquelen, (int64_t) RemainingBufferSpace(result)); +               errorcode = SLP_ERROR_PARSE_ERROR; +               goto FINISHED; +             } } } } </ins>

Discussion:
, CVSSv3=9.8 (nixos-19.03, nixos-19.09, nixos-unstable) Scanned versions: nixos-19.03: ; nixos-19.09: ; nixos-unstable: . May contain false positives.
03 is out of support - we don't backport security fixes there anymore.
But this was also about nixos-unstable.
This was a grave mistake from your side. See