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authorFlorian Weimer <fweimer@redhat.com>2016-12-31 20:22:09 +0100
committerFlorian Weimer <fweimer@redhat.com>2016-12-31 20:27:44 +0100
commitfc82b0a2dfe7dbd35671c10510a8da1043d746a5 (patch)
tree86b8ef6421ca34fa1907121e078e008c580029ea
parent3c589b1a8a4401e258ba23a03fcbcc79b82393ab (diff)
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CVE-2015-5180: resolv: Fix crash with internal QTYPE [BZ #18784]
Also rename T_UNSPEC because an upcoming public header file update will use that name.
-rw-r--r--ChangeLog14
-rw-r--r--NEWS8
-rw-r--r--include/arpa/nameser_compat.h6
-rw-r--r--resolv/Makefile3
-rw-r--r--resolv/nss_dns/dns-host.c2
-rw-r--r--resolv/res_mkquery.c4
-rw-r--r--resolv/res_query.c6
-rw-r--r--resolv/tst-resolv-qtypes.c185
8 files changed, 220 insertions, 8 deletions
diff --git a/ChangeLog b/ChangeLog
index 01ee23b..3beacb0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,19 @@
2016-12-31 Florian Weimer <fweimer@redhat.com>
+ [BZ #18784]
+ CVE-2015-5180
+ * include/arpa/nameser_compat.h (T_QUERY_A_AND_AAAA): Rename from
+ T_UNSPEC. Adjust value.
+ * resolv/nss_dns/dns-host.c (_nss_dns_gethostbyname4_r): Use it.
+ * resolv/res_query.c (__libc_res_nquery): Likewise.
+ * resolv/res_mkquery.c (res_nmkquery): Check for out-of-range
+ QTYPEs.
+ * resolv/tst-resolv-qtypes.c: New file.
+ * resolv/Makefile (xtests): Add tst-resolv-qtypes.
+ (tst-resolv-qtypes): Link against libresolv and libpthread.
+
+2016-12-31 Florian Weimer <fweimer@redhat.com>
+
* elf/dl-tunables.h (__tunables_init): Fix unused attribute.
2016-12-31 Siddhesh Poyarekar <siddhesh@sourceware.org>
diff --git a/NEWS b/NEWS
index 7ebce44..08b566d 100644
--- a/NEWS
+++ b/NEWS
@@ -191,12 +191,18 @@ Version 2.25
Security related changes:
- On ARM EABI (32-bit), generating a backtrace for execution contexts which
+* On ARM EABI (32-bit), generating a backtrace for execution contexts which
have been created with makecontext could fail to terminate due to a
missing .cantunwind annotation. This has been observed to lead to a hang
(denial of service) in some Go applications compiled with gccgo. Reported
by Andreas Schwab. (CVE-2016-6323)
+* The DNS stub resolver functions would crash due to a NULL pointer
+ dereference when processing a query with a valid DNS question type which
+ was used internally in the implementation. The stub resolver now uses a
+ question type which is outside the range of valid question type values.
+ (CVE-2015-5180)
+
The following bugs are resolved with this release:
[The release manager will add the list generated by
diff --git a/include/arpa/nameser_compat.h b/include/arpa/nameser_compat.h
index 6928000..f7d0e04 100644
--- a/include/arpa/nameser_compat.h
+++ b/include/arpa/nameser_compat.h
@@ -3,9 +3,9 @@
# ifndef _ISOMAC
-/* Picksome unused number to represent lookups of IPv4 and IPv6 (i.e.,
- T_A and T_AAAA). */
-#define T_UNSPEC 62321
+/* The number is outside the 16-bit RR type range and is used
+ internally by the implementation. */
+#define T_QUERY_A_AND_AAAA 439963904
# endif /* !_ISOMAC */
#endif
diff --git a/resolv/Makefile b/resolv/Makefile
index 1e9f562..1089995 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -49,6 +49,8 @@ tests += \
tst-resolv-network \
tst-resolv-search \
+# This test sends millions of packets and is rather slow.
+xtests += tst-resolv-qtypes
endif
extra-libs-others = $(extra-libs)
libresolv-routines := res_comp res_debug \
@@ -123,6 +125,7 @@ $(objpfx)tst-bug18665: $(objpfx)libresolv.so $(shared-thread-library)
$(objpfx)tst-res_use_inet6: $(objpfx)libresolv.so $(shared-thread-library)
$(objpfx)tst-resolv-basic: $(objpfx)libresolv.so $(shared-thread-library)
$(objpfx)tst-resolv-network: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-resolv-qtypes: $(objpfx)libresolv.so $(shared-thread-library)
$(objpfx)tst-resolv-search: $(objpfx)libresolv.so $(shared-thread-library)
# This test case uses the deprecated RES_USE_INET6 resolver option.
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index 901e037..d597faa 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -324,7 +324,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
int olderr = errno;
enum nss_status status;
- int n = __libc_res_nsearch (&_res, name, C_IN, T_UNSPEC,
+ int n = __libc_res_nsearch (&_res, name, C_IN, T_QUERY_A_AND_AAAA,
host_buffer.buf->buf, 2048, &host_buffer.ptr,
&ans2p, &nans2p, &resplen2, &ans2p_malloced);
if (n >= 0)
diff --git a/resolv/res_mkquery.c b/resolv/res_mkquery.c
index 12f9730..d80b531 100644
--- a/resolv/res_mkquery.c
+++ b/resolv/res_mkquery.c
@@ -103,6 +103,10 @@ res_nmkquery(res_state statp,
int n;
u_char *dnptrs[20], **dpp, **lastdnptr;
+ if (class < 0 || class > 65535
+ || type < 0 || type > 65535)
+ return -1;
+
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf(";; res_nmkquery(%s, %s, %s, %s)\n",
diff --git a/resolv/res_query.c b/resolv/res_query.c
index 944d1a9..07dc6f6 100644
--- a/resolv/res_query.c
+++ b/resolv/res_query.c
@@ -122,7 +122,7 @@ __libc_res_nquery(res_state statp,
int n, use_malloc = 0;
u_int oflags = statp->_flags;
- size_t bufsize = (type == T_UNSPEC ? 2 : 1) * QUERYSIZE;
+ size_t bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * QUERYSIZE;
u_char *buf = alloca (bufsize);
u_char *query1 = buf;
int nquery1 = -1;
@@ -137,7 +137,7 @@ __libc_res_nquery(res_state statp,
printf(";; res_query(%s, %d, %d)\n", name, class, type);
#endif
- if (type == T_UNSPEC)
+ if (type == T_QUERY_A_AND_AAAA)
{
n = res_nmkquery(statp, QUERY, name, class, T_A, NULL, 0, NULL,
query1, bufsize);
@@ -190,7 +190,7 @@ __libc_res_nquery(res_state statp,
if (__builtin_expect (n <= 0, 0) && !use_malloc) {
/* Retry just in case res_nmkquery failed because of too
short buffer. Shouldn't happen. */
- bufsize = (type == T_UNSPEC ? 2 : 1) * MAXPACKET;
+ bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * MAXPACKET;
buf = malloc (bufsize);
if (buf != NULL) {
query1 = buf;
diff --git a/resolv/tst-resolv-qtypes.c b/resolv/tst-resolv-qtypes.c
new file mode 100644
index 0000000..b3e60c6
--- /dev/null
+++ b/resolv/tst-resolv-qtypes.c
@@ -0,0 +1,185 @@
+/* Exercise low-level query functions with different QTYPEs.
+ 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/>. */
+
+#include <resolv.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/support.h>
+#include <support/test-driver.h>
+#include <support/xmemstream.h>
+
+/* If ture, the response function will send the actual response packet
+ over TCP instead of UDP. */
+static volatile bool force_tcp;
+
+/* Send back a fake resource record matching the QTYPE. */
+static void
+response (const struct resolv_response_context *ctx,
+ struct resolv_response_builder *b,
+ const char *qname, uint16_t qclass, uint16_t qtype)
+{
+ if (force_tcp && ctx->tcp)
+ {
+ resolv_response_init (b, (struct resolv_response_flags) { .tc = 1 });
+ resolv_response_add_question (b, qname, qclass, qtype);
+ return;
+ }
+
+ resolv_response_init (b, (struct resolv_response_flags) { });
+ resolv_response_add_question (b, qname, qclass, qtype);
+ resolv_response_section (b, ns_s_an);
+ resolv_response_open_record (b, qname, qclass, qtype, 0);
+ resolv_response_add_data (b, &qtype, sizeof (qtype));
+ resolv_response_close_record (b);
+}
+
+static const const char *domain = "www.example.com";
+
+static int
+wrap_res_query (int type, unsigned char *answer, int answer_length)
+{
+ return res_query (domain, C_IN, type, answer, answer_length);
+}
+
+static int
+wrap_res_search (int type, unsigned char *answer, int answer_length)
+{
+ return res_query (domain, C_IN, type, answer, answer_length);
+}
+
+static int
+wrap_res_querydomain (int type, unsigned char *answer, int answer_length)
+{
+ return res_querydomain ("www", "example.com", C_IN, type,
+ answer, answer_length);
+}
+
+static int
+wrap_res_send (int type, unsigned char *answer, int answer_length)
+{
+ unsigned char buf[512];
+ int ret = res_mkquery (QUERY, domain, C_IN, type,
+ (const unsigned char *) "", 0, NULL,
+ buf, sizeof (buf));
+ if (type < 0 || type >= 65536)
+ {
+ /* res_mkquery fails for out-of-range record types. */
+ TEST_VERIFY_EXIT (ret == -1);
+ return -1;
+ }
+ TEST_VERIFY_EXIT (ret > 12); /* DNS header length. */
+ return res_send (buf, ret, answer, answer_length);
+}
+
+static int
+wrap_res_nquery (int type, unsigned char *answer, int answer_length)
+{
+ return res_nquery (&_res, domain, C_IN, type, answer, answer_length);
+}
+
+static int
+wrap_res_nsearch (int type, unsigned char *answer, int answer_length)
+{
+ return res_nquery (&_res, domain, C_IN, type, answer, answer_length);
+}
+
+static int
+wrap_res_nquerydomain (int type, unsigned char *answer, int answer_length)
+{
+ return res_nquerydomain (&_res, "www", "example.com", C_IN, type,
+ answer, answer_length);
+}
+
+static int
+wrap_res_nsend (int type, unsigned char *answer, int answer_length)
+{
+ unsigned char buf[512];
+ int ret = res_nmkquery (&_res, QUERY, domain, C_IN, type,
+ (const unsigned char *) "", 0, NULL,
+ buf, sizeof (buf));
+ if (type < 0 || type >= 65536)
+ {
+ /* res_mkquery fails for out-of-range record types. */
+ TEST_VERIFY_EXIT (ret == -1);
+ return -1;
+ }
+ TEST_VERIFY_EXIT (ret > 12); /* DNS header length. */
+ return res_nsend (&_res, buf, ret, answer, answer_length);
+}
+
+static void
+test_function (const char *fname,
+ int (*func) (int type,
+ unsigned char *answer, int answer_length))
+{
+ unsigned char buf[512];
+ for (int tcp = 0; tcp < 2; ++tcp)
+ {
+ force_tcp = tcp;
+ for (unsigned int type = 1; type <= 65535; ++type)
+ {
+ if (test_verbose)
+ printf ("info: sending QTYPE %d with %s (tcp=%d)\n",
+ type, fname, tcp);
+ int ret = func (type, buf, sizeof (buf));
+ if (ret != 47)
+ FAIL_EXIT1 ("%s tcp=%d qtype=%d return value %d",
+ fname,tcp, type, ret);
+ /* One question, one answer record. */
+ TEST_VERIFY (memcmp (buf + 4, "\0\1\0\1\0\0\0\0", 8) == 0);
+ /* Question section. */
+ static const char qname[] = "\3www\7example\3com";
+ size_t qname_length = sizeof (qname);
+ TEST_VERIFY (memcmp (buf + 12, qname, qname_length) == 0);
+ /* RDATA part of answer. */
+ uint16_t type16 = type;
+ TEST_VERIFY (memcmp (buf + ret - 2, &type16, sizeof (type16)) == 0);
+ }
+ }
+
+ TEST_VERIFY (func (-1, buf, sizeof (buf) == -1));
+ TEST_VERIFY (func (65536, buf, sizeof (buf) == -1));
+}
+
+static int
+do_test (void)
+{
+ struct resolv_redirect_config config =
+ {
+ .response_callback = response,
+ };
+ struct resolv_test *obj = resolv_test_start (config);
+
+ test_function ("res_query", &wrap_res_query);
+ test_function ("res_search", &wrap_res_search);
+ test_function ("res_querydomain", &wrap_res_querydomain);
+ test_function ("res_send", &wrap_res_send);
+
+ test_function ("res_nquery", &wrap_res_nquery);
+ test_function ("res_nsearch", &wrap_res_nsearch);
+ test_function ("res_nquerydomain", &wrap_res_nquerydomain);
+ test_function ("res_nsend", &wrap_res_nsend);
+
+ resolv_test_end (obj);
+ return 0;
+}
+
+#define TIMEOUT 300
+#include <support/test-driver.c>