diff options
Diffstat (limited to 'gnu/packages/patches/glibc-CVE-2015-7547.patch')
| -rw-r--r-- | gnu/packages/patches/glibc-CVE-2015-7547.patch | 590 |
1 files changed, 0 insertions, 590 deletions
diff --git a/gnu/packages/patches/glibc-CVE-2015-7547.patch b/gnu/packages/patches/glibc-CVE-2015-7547.patch deleted file mode 100644 index 12abeb76d4..0000000000 --- a/gnu/packages/patches/glibc-CVE-2015-7547.patch +++ /dev/null @@ -1,590 +0,0 @@ -From b995d95a5943785be3ab862b2d3276f3b4a22481 Mon Sep 17 00:00:00 2001 -From: Carlos O'Donell <carlos@systemhalted.org> -Date: Tue, 16 Feb 2016 21:26:37 -0500 -Subject: [PATCH] CVE-2015-7547: getaddrinfo() stack-based buffer overflow (Bug - 18665). - -* A stack-based buffer overflow was found in libresolv when invoked from - libnss_dns, allowing specially crafted DNS responses to seize control - of execution flow in the DNS client. The buffer overflow occurs in - the functions send_dg (send datagram) and send_vc (send TCP) for the - NSS module libnss_dns.so.2 when calling getaddrinfo with AF_UNSPEC - family. The use of AF_UNSPEC triggers the low-level resolver code to - send out two parallel queries for A and AAAA. A mismanagement of the - buffers used for those queries could result in the response of a query - writing beyond the alloca allocated buffer created by - _nss_dns_gethostbyname4_r. Buffer management is simplified to remove - the overflow. Thanks to the Google Security Team and Red Hat for - reporting the security impact of this issue, and Robert Holiday of - Ciena for reporting the related bug 18665. (CVE-2015-7547) - -See also: -https://sourceware.org/ml/libc-alpha/2016-02/msg00416.html -https://sourceware.org/ml/libc-alpha/2016-02/msg00418.html - -(cherry picked from commit e9db92d3acfe1822d56d11abcea5bfc4c41cf6ca) ---- - ChangeLog | 15 +++ - NEWS | 14 +++ - resolv/nss_dns/dns-host.c | 111 ++++++++++++++++++- - resolv/res_query.c | 3 + - resolv/res_send.c | 264 ++++++++++++++++++++++++++++++++++------------ - 5 files changed, 338 insertions(+), 69 deletions(-) - -diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c -index 357ac04..a0fe9a8 100644 ---- a/resolv/nss_dns/dns-host.c -+++ b/resolv/nss_dns/dns-host.c -@@ -1031,7 +1031,10 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname, - int h_namelen = 0; - - if (ancount == 0) -- return NSS_STATUS_NOTFOUND; -+ { -+ *h_errnop = HOST_NOT_FOUND; -+ return NSS_STATUS_NOTFOUND; -+ } - - while (ancount-- > 0 && cp < end_of_message && had_error == 0) - { -@@ -1208,7 +1211,14 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname, - /* Special case here: if the resolver sent a result but it only - contains a CNAME while we are looking for a T_A or T_AAAA record, - we fail with NOTFOUND instead of TRYAGAIN. */ -- return canon == NULL ? NSS_STATUS_TRYAGAIN : NSS_STATUS_NOTFOUND; -+ if (canon != NULL) -+ { -+ *h_errnop = HOST_NOT_FOUND; -+ return NSS_STATUS_NOTFOUND; -+ } -+ -+ *h_errnop = NETDB_INTERNAL; -+ return NSS_STATUS_TRYAGAIN; - } - - -@@ -1222,11 +1232,101 @@ gaih_getanswer (const querybuf *answer1, int anslen1, const querybuf *answer2, - - enum nss_status status = NSS_STATUS_NOTFOUND; - -+ /* Combining the NSS status of two distinct queries requires some -+ compromise and attention to symmetry (A or AAAA queries can be -+ returned in any order). What follows is a breakdown of how this -+ code is expected to work and why. We discuss only SUCCESS, -+ TRYAGAIN, NOTFOUND and UNAVAIL, since they are the only returns -+ that apply (though RETURN and MERGE exist). We make a distinction -+ between TRYAGAIN (recoverable) and TRYAGAIN' (not-recoverable). -+ A recoverable TRYAGAIN is almost always due to buffer size issues -+ and returns ERANGE in errno and the caller is expected to retry -+ with a larger buffer. -+ -+ Lastly, you may be tempted to make significant changes to the -+ conditions in this code to bring about symmetry between responses. -+ Please don't change anything without due consideration for -+ expected application behaviour. Some of the synthesized responses -+ aren't very well thought out and sometimes appear to imply that -+ IPv4 responses are always answer 1, and IPv6 responses are always -+ answer 2, but that's not true (see the implementation of send_dg -+ and send_vc to see response can arrive in any order, particularly -+ for UDP). However, we expect it holds roughly enough of the time -+ that this code works, but certainly needs to be fixed to make this -+ a more robust implementation. -+ -+ ---------------------------------------------- -+ | Answer 1 Status / | Synthesized | Reason | -+ | Answer 2 Status | Status | | -+ |--------------------------------------------| -+ | SUCCESS/SUCCESS | SUCCESS | [1] | -+ | SUCCESS/TRYAGAIN | TRYAGAIN | [5] | -+ | SUCCESS/TRYAGAIN' | SUCCESS | [1] | -+ | SUCCESS/NOTFOUND | SUCCESS | [1] | -+ | SUCCESS/UNAVAIL | SUCCESS | [1] | -+ | TRYAGAIN/SUCCESS | TRYAGAIN | [2] | -+ | TRYAGAIN/TRYAGAIN | TRYAGAIN | [2] | -+ | TRYAGAIN/TRYAGAIN' | TRYAGAIN | [2] | -+ | TRYAGAIN/NOTFOUND | TRYAGAIN | [2] | -+ | TRYAGAIN/UNAVAIL | TRYAGAIN | [2] | -+ | TRYAGAIN'/SUCCESS | SUCCESS | [3] | -+ | TRYAGAIN'/TRYAGAIN | TRYAGAIN | [3] | -+ | TRYAGAIN'/TRYAGAIN' | TRYAGAIN' | [3] | -+ | TRYAGAIN'/NOTFOUND | TRYAGAIN' | [3] | -+ | TRYAGAIN'/UNAVAIL | UNAVAIL | [3] | -+ | NOTFOUND/SUCCESS | SUCCESS | [3] | -+ | NOTFOUND/TRYAGAIN | TRYAGAIN | [3] | -+ | NOTFOUND/TRYAGAIN' | TRYAGAIN' | [3] | -+ | NOTFOUND/NOTFOUND | NOTFOUND | [3] | -+ | NOTFOUND/UNAVAIL | UNAVAIL | [3] | -+ | UNAVAIL/SUCCESS | UNAVAIL | [4] | -+ | UNAVAIL/TRYAGAIN | UNAVAIL | [4] | -+ | UNAVAIL/TRYAGAIN' | UNAVAIL | [4] | -+ | UNAVAIL/NOTFOUND | UNAVAIL | [4] | -+ | UNAVAIL/UNAVAIL | UNAVAIL | [4] | -+ ---------------------------------------------- -+ -+ [1] If the first response is a success we return success. -+ This ignores the state of the second answer and in fact -+ incorrectly sets errno and h_errno to that of the second -+ answer. However because the response is a success we ignore -+ *errnop and *h_errnop (though that means you touched errno on -+ success). We are being conservative here and returning the -+ likely IPv4 response in the first answer as a success. -+ -+ [2] If the first response is a recoverable TRYAGAIN we return -+ that instead of looking at the second response. The -+ expectation here is that we have failed to get an IPv4 response -+ and should retry both queries. -+ -+ [3] If the first response was not a SUCCESS and the second -+ response is not NOTFOUND (had a SUCCESS, need to TRYAGAIN, -+ or failed entirely e.g. TRYAGAIN' and UNAVAIL) then use the -+ result from the second response, otherwise the first responses -+ status is used. Again we have some odd side-effects when the -+ second response is NOTFOUND because we overwrite *errnop and -+ *h_errnop that means that a first answer of NOTFOUND might see -+ its *errnop and *h_errnop values altered. Whether it matters -+ in practice that a first response NOTFOUND has the wrong -+ *errnop and *h_errnop is undecided. -+ -+ [4] If the first response is UNAVAIL we return that instead of -+ looking at the second response. The expectation here is that -+ it will have failed similarly e.g. configuration failure. -+ -+ [5] Testing this code is complicated by the fact that truncated -+ second response buffers might be returned as SUCCESS if the -+ first answer is a SUCCESS. To fix this we add symmetry to -+ TRYAGAIN with the second response. If the second response -+ is a recoverable error we now return TRYAGIN even if the first -+ response was SUCCESS. */ -+ - if (anslen1 > 0) - status = gaih_getanswer_slice(answer1, anslen1, qname, - &pat, &buffer, &buflen, - errnop, h_errnop, ttlp, - &first); -+ - if ((status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND - || (status == NSS_STATUS_TRYAGAIN - /* We want to look at the second answer in case of an -@@ -1242,8 +1342,15 @@ gaih_getanswer (const querybuf *answer1, int anslen1, const querybuf *answer2, - &pat, &buffer, &buflen, - errnop, h_errnop, ttlp, - &first); -+ /* Use the second response status in some cases. */ - if (status != NSS_STATUS_SUCCESS && status2 != NSS_STATUS_NOTFOUND) - status = status2; -+ /* Do not return a truncated second response (unless it was -+ unavoidable e.g. unrecoverable TRYAGAIN). */ -+ if (status == NSS_STATUS_SUCCESS -+ && (status2 == NSS_STATUS_TRYAGAIN -+ && *errnop == ERANGE && *h_errnop != NO_RECOVERY)) -+ status = NSS_STATUS_TRYAGAIN; - } - - return status; -diff --git a/resolv/res_query.c b/resolv/res_query.c -index 4a9b3b3..95470a9 100644 ---- a/resolv/res_query.c -+++ b/resolv/res_query.c -@@ -396,6 +396,7 @@ __libc_res_nsearch(res_state statp, - { - free (*answerp2); - *answerp2 = NULL; -+ *nanswerp2 = 0; - *answerp2_malloced = 0; - } - } -@@ -447,6 +448,7 @@ __libc_res_nsearch(res_state statp, - { - free (*answerp2); - *answerp2 = NULL; -+ *nanswerp2 = 0; - *answerp2_malloced = 0; - } - -@@ -521,6 +523,7 @@ __libc_res_nsearch(res_state statp, - { - free (*answerp2); - *answerp2 = NULL; -+ *nanswerp2 = 0; - *answerp2_malloced = 0; - } - if (saved_herrno != -1) -diff --git a/resolv/res_send.c b/resolv/res_send.c -index 5e53cc2..6511bb1 100644 ---- a/resolv/res_send.c -+++ b/resolv/res_send.c -@@ -1,3 +1,20 @@ -+/* Copyright (C) 2016 Free Software Foundation, Inc. -+ This file is part of the GNU C Library. -+ -+ The GNU C Library is free software; you can redistribute it and/or -+ modify it under the terms of the GNU Lesser General Public -+ License as published by the Free Software Foundation; either -+ version 2.1 of the License, or (at your option) any later version. -+ -+ The GNU C Library is distributed in the hope that it will be useful, -+ but WITHOUT ANY WARRANTY; without even the implied warranty of -+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU -+ Lesser General Public License for more details. -+ -+ You should have received a copy of the GNU Lesser General Public -+ License along with the GNU C Library; if not, see -+ <http://www.gnu.org/licenses/>. */ -+ - /* - * Copyright (c) 1985, 1989, 1993 - * The Regents of the University of California. All rights reserved. -@@ -363,6 +380,8 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen, - #ifdef USE_HOOKS - if (__glibc_unlikely (statp->qhook || statp->rhook)) { - if (anssiz < MAXPACKET && ansp) { -+ /* Always allocate MAXPACKET, callers expect -+ this specific size. */ - u_char *buf = malloc (MAXPACKET); - if (buf == NULL) - return (-1); -@@ -638,6 +657,77 @@ get_nsaddr (res_state statp, int n) - return (struct sockaddr *) (void *) &statp->nsaddr_list[n]; - } - -+/* The send_vc function is responsible for sending a DNS query over TCP -+ to the nameserver numbered NS from the res_state STATP i.e. -+ EXT(statp).nssocks[ns]. The function supports sending both IPv4 and -+ IPv6 queries at the same serially on the same socket. -+ -+ Please note that for TCP there is no way to disable sending both -+ queries, unlike UDP, which honours RES_SNGLKUP and RES_SNGLKUPREOP -+ and sends the queries serially and waits for the result after each -+ sent query. This implemetnation should be corrected to honour these -+ options. -+ -+ Please also note that for TCP we send both queries over the same -+ socket one after another. This technically violates best practice -+ since the server is allowed to read the first query, respond, and -+ then close the socket (to service another client). If the server -+ does this, then the remaining second query in the socket data buffer -+ will cause the server to send the client an RST which will arrive -+ asynchronously and the client's OS will likely tear down the socket -+ receive buffer resulting in a potentially short read and lost -+ response data. This will force the client to retry the query again, -+ and this process may repeat until all servers and connection resets -+ are exhausted and then the query will fail. It's not known if this -+ happens with any frequency in real DNS server implementations. This -+ implementation should be corrected to use two sockets by default for -+ parallel queries. -+ -+ The query stored in BUF of BUFLEN length is sent first followed by -+ the query stored in BUF2 of BUFLEN2 length. Queries are sent -+ serially on the same socket. -+ -+ Answers to the query are stored firstly in *ANSP up to a max of -+ *ANSSIZP bytes. If more than *ANSSIZP bytes are needed and ANSCP -+ is non-NULL (to indicate that modifying the answer buffer is allowed) -+ then malloc is used to allocate a new response buffer and ANSCP and -+ ANSP will both point to the new buffer. If more than *ANSSIZP bytes -+ are needed but ANSCP is NULL, then as much of the response as -+ possible is read into the buffer, but the results will be truncated. -+ When truncation happens because of a small answer buffer the DNS -+ packets header field TC will bet set to 1, indicating a truncated -+ message and the rest of the socket data will be read and discarded. -+ -+ Answers to the query are stored secondly in *ANSP2 up to a max of -+ *ANSSIZP2 bytes, with the actual response length stored in -+ *RESPLEN2. If more than *ANSSIZP bytes are needed and ANSP2 -+ is non-NULL (required for a second query) then malloc is used to -+ allocate a new response buffer, *ANSSIZP2 is set to the new buffer -+ size and *ANSP2_MALLOCED is set to 1. -+ -+ The ANSP2_MALLOCED argument will eventually be removed as the -+ change in buffer pointer can be used to detect the buffer has -+ changed and that the caller should use free on the new buffer. -+ -+ Note that the answers may arrive in any order from the server and -+ therefore the first and second answer buffers may not correspond to -+ the first and second queries. -+ -+ It is not supported to call this function with a non-NULL ANSP2 -+ but a NULL ANSCP. Put another way, you can call send_vc with a -+ single unmodifiable buffer or two modifiable buffers, but no other -+ combination is supported. -+ -+ It is the caller's responsibility to free the malloc allocated -+ buffers by detecting that the pointers have changed from their -+ original values i.e. *ANSCP or *ANSP2 has changed. -+ -+ If errors are encountered then *TERRNO is set to an appropriate -+ errno value and a zero result is returned for a recoverable error, -+ and a less-than zero result is returned for a non-recoverable error. -+ -+ If no errors are encountered then *TERRNO is left unmodified and -+ a the length of the first response in bytes is returned. */ - static int - send_vc(res_state statp, - const u_char *buf, int buflen, const u_char *buf2, int buflen2, -@@ -647,11 +737,7 @@ send_vc(res_state statp, - { - const HEADER *hp = (HEADER *) buf; - const HEADER *hp2 = (HEADER *) buf2; -- u_char *ans = *ansp; -- int orig_anssizp = *anssizp; -- // XXX REMOVE -- // int anssiz = *anssizp; -- HEADER *anhp = (HEADER *) ans; -+ HEADER *anhp = (HEADER *) *ansp; - struct sockaddr *nsap = get_nsaddr (statp, ns); - int truncating, connreset, n; - /* On some architectures compiler might emit a warning indicating -@@ -743,6 +829,8 @@ send_vc(res_state statp, - * Receive length & response - */ - int recvresp1 = 0; -+ /* Skip the second response if there is no second query. -+ To do that we mark the second response as received. */ - int recvresp2 = buf2 == NULL; - uint16_t rlen16; - read_len: -@@ -779,40 +867,14 @@ send_vc(res_state statp, - u_char **thisansp; - int *thisresplenp; - if ((recvresp1 | recvresp2) == 0 || buf2 == NULL) { -+ /* We have not received any responses -+ yet or we only have one response to -+ receive. */ - thisanssizp = anssizp; - thisansp = anscp ?: ansp; - assert (anscp != NULL || ansp2 == NULL); - thisresplenp = &resplen; - } else { -- if (*anssizp != MAXPACKET) { -- /* No buffer allocated for the first -- reply. We can try to use the rest -- of the user-provided buffer. */ --#if __GNUC_PREREQ (4, 7) -- DIAG_PUSH_NEEDS_COMMENT; -- DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized"); --#endif --#if _STRING_ARCH_unaligned -- *anssizp2 = orig_anssizp - resplen; -- *ansp2 = *ansp + resplen; --#else -- int aligned_resplen -- = ((resplen + __alignof__ (HEADER) - 1) -- & ~(__alignof__ (HEADER) - 1)); -- *anssizp2 = orig_anssizp - aligned_resplen; -- *ansp2 = *ansp + aligned_resplen; --#endif --#if __GNUC_PREREQ (4, 7) -- DIAG_POP_NEEDS_COMMENT; --#endif -- } else { -- /* The first reply did not fit into the -- user-provided buffer. Maybe the second -- answer will. */ -- *anssizp2 = orig_anssizp; -- *ansp2 = *ansp; -- } -- - thisanssizp = anssizp2; - thisansp = ansp2; - thisresplenp = resplen2; -@@ -820,10 +882,14 @@ send_vc(res_state statp, - anhp = (HEADER *) *thisansp; - - *thisresplenp = rlen; -- if (rlen > *thisanssizp) { -- /* Yes, we test ANSCP here. If we have two buffers -- both will be allocatable. */ -- if (__glibc_likely (anscp != NULL)) { -+ /* Is the answer buffer too small? */ -+ if (*thisanssizp < rlen) { -+ /* If the current buffer is not the the static -+ user-supplied buffer then we can reallocate -+ it. */ -+ if (thisansp != NULL && thisansp != ansp) { -+ /* Always allocate MAXPACKET, callers expect -+ this specific size. */ - u_char *newp = malloc (MAXPACKET); - if (newp == NULL) { - *terrno = ENOMEM; -@@ -835,6 +901,9 @@ send_vc(res_state statp, - if (thisansp == ansp2) - *ansp2_malloced = 1; - anhp = (HEADER *) newp; -+ /* A uint16_t can't be larger than MAXPACKET -+ thus it's safe to allocate MAXPACKET but -+ read RLEN bytes instead. */ - len = rlen; - } else { - Dprint(statp->options & RES_DEBUG, -@@ -997,6 +1066,66 @@ reopen (res_state statp, int *terrno, int ns) - return 1; - } - -+/* The send_dg function is responsible for sending a DNS query over UDP -+ to the nameserver numbered NS from the res_state STATP i.e. -+ EXT(statp).nssocks[ns]. The function supports IPv4 and IPv6 queries -+ along with the ability to send the query in parallel for both stacks -+ (default) or serially (RES_SINGLKUP). It also supports serial lookup -+ with a close and reopen of the socket used to talk to the server -+ (RES_SNGLKUPREOP) to work around broken name servers. -+ -+ The query stored in BUF of BUFLEN length is sent first followed by -+ the query stored in BUF2 of BUFLEN2 length. Queries are sent -+ in parallel (default) or serially (RES_SINGLKUP or RES_SNGLKUPREOP). -+ -+ Answers to the query are stored firstly in *ANSP up to a max of -+ *ANSSIZP bytes. If more than *ANSSIZP bytes are needed and ANSCP -+ is non-NULL (to indicate that modifying the answer buffer is allowed) -+ then malloc is used to allocate a new response buffer and ANSCP and -+ ANSP will both point to the new buffer. If more than *ANSSIZP bytes -+ are needed but ANSCP is NULL, then as much of the response as -+ possible is read into the buffer, but the results will be truncated. -+ When truncation happens because of a small answer buffer the DNS -+ packets header field TC will bet set to 1, indicating a truncated -+ message, while the rest of the UDP packet is discarded. -+ -+ Answers to the query are stored secondly in *ANSP2 up to a max of -+ *ANSSIZP2 bytes, with the actual response length stored in -+ *RESPLEN2. If more than *ANSSIZP bytes are needed and ANSP2 -+ is non-NULL (required for a second query) then malloc is used to -+ allocate a new response buffer, *ANSSIZP2 is set to the new buffer -+ size and *ANSP2_MALLOCED is set to 1. -+ -+ The ANSP2_MALLOCED argument will eventually be removed as the -+ change in buffer pointer can be used to detect the buffer has -+ changed and that the caller should use free on the new buffer. -+ -+ Note that the answers may arrive in any order from the server and -+ therefore the first and second answer buffers may not correspond to -+ the first and second queries. -+ -+ It is not supported to call this function with a non-NULL ANSP2 -+ but a NULL ANSCP. Put another way, you can call send_vc with a -+ single unmodifiable buffer or two modifiable buffers, but no other -+ combination is supported. -+ -+ It is the caller's responsibility to free the malloc allocated -+ buffers by detecting that the pointers have changed from their -+ original values i.e. *ANSCP or *ANSP2 has changed. -+ -+ If an answer is truncated because of UDP datagram DNS limits then -+ *V_CIRCUIT is set to 1 and the return value non-zero to indicate to -+ the caller to retry with TCP. The value *GOTSOMEWHERE is set to 1 -+ if any progress was made reading a response from the nameserver and -+ is used by the caller to distinguish between ECONNREFUSED and -+ ETIMEDOUT (the latter if *GOTSOMEWHERE is 1). -+ -+ If errors are encountered then *TERRNO is set to an appropriate -+ errno value and a zero result is returned for a recoverable error, -+ and a less-than zero result is returned for a non-recoverable error. -+ -+ If no errors are encountered then *TERRNO is left unmodified and -+ a the length of the first response in bytes is returned. */ - static int - send_dg(res_state statp, - const u_char *buf, int buflen, const u_char *buf2, int buflen2, -@@ -1006,8 +1135,6 @@ send_dg(res_state statp, - { - const HEADER *hp = (HEADER *) buf; - const HEADER *hp2 = (HEADER *) buf2; -- u_char *ans = *ansp; -- int orig_anssizp = *anssizp; - struct timespec now, timeout, finish; - struct pollfd pfd[1]; - int ptimeout; -@@ -1040,6 +1167,8 @@ send_dg(res_state statp, - int need_recompute = 0; - int nwritten = 0; - int recvresp1 = 0; -+ /* Skip the second response if there is no second query. -+ To do that we mark the second response as received. */ - int recvresp2 = buf2 == NULL; - pfd[0].fd = EXT(statp).nssocks[ns]; - pfd[0].events = POLLOUT; -@@ -1203,55 +1332,56 @@ send_dg(res_state statp, - int *thisresplenp; - - if ((recvresp1 | recvresp2) == 0 || buf2 == NULL) { -+ /* We have not received any responses -+ yet or we only have one response to -+ receive. */ - thisanssizp = anssizp; - thisansp = anscp ?: ansp; - assert (anscp != NULL || ansp2 == NULL); - thisresplenp = &resplen; - } else { -- if (*anssizp != MAXPACKET) { -- /* No buffer allocated for the first -- reply. We can try to use the rest -- of the user-provided buffer. */ --#if _STRING_ARCH_unaligned -- *anssizp2 = orig_anssizp - resplen; -- *ansp2 = *ansp + resplen; --#else -- int aligned_resplen -- = ((resplen + __alignof__ (HEADER) - 1) -- & ~(__alignof__ (HEADER) - 1)); -- *anssizp2 = orig_anssizp - aligned_resplen; -- *ansp2 = *ansp + aligned_resplen; --#endif -- } else { -- /* The first reply did not fit into the -- user-provided buffer. Maybe the second -- answer will. */ -- *anssizp2 = orig_anssizp; -- *ansp2 = *ansp; -- } -- - thisanssizp = anssizp2; - thisansp = ansp2; - thisresplenp = resplen2; - } - - if (*thisanssizp < MAXPACKET -- /* Yes, we test ANSCP here. If we have two buffers -- both will be allocatable. */ -- && anscp -+ /* If the current buffer is not the the static -+ user-supplied buffer then we can reallocate -+ it. */ -+ && (thisansp != NULL && thisansp != ansp) - #ifdef FIONREAD -+ /* Is the size too small? */ - && (ioctl (pfd[0].fd, FIONREAD, thisresplenp) < 0 - || *thisanssizp < *thisresplenp) - #endif - ) { -+ /* Always allocate MAXPACKET, callers expect -+ this specific size. */ - u_char *newp = malloc (MAXPACKET); - if (newp != NULL) { -- *anssizp = MAXPACKET; -- *thisansp = ans = newp; -+ *thisanssizp = MAXPACKET; -+ *thisansp = newp; - if (thisansp == ansp2) - *ansp2_malloced = 1; - } - } -+ /* We could end up with truncation if anscp was NULL -+ (not allowed to change caller's buffer) and the -+ response buffer size is too small. This isn't a -+ reliable way to detect truncation because the ioctl -+ may be an inaccurate report of the UDP message size. -+ Therefore we use this only to issue debug output. -+ To do truncation accurately with UDP we need -+ MSG_TRUNC which is only available on Linux. We -+ can abstract out the Linux-specific feature in the -+ future to detect truncation. */ -+ if (__glibc_unlikely (*thisanssizp < *thisresplenp)) { -+ Dprint(statp->options & RES_DEBUG, -+ (stdout, ";; response may be truncated (UDP)\n") -+ ); -+ } -+ - HEADER *anhp = (HEADER *) *thisansp; - socklen_t fromlen = sizeof(struct sockaddr_in6); - assert (sizeof(from) <= fromlen); --- -2.9.3 - |