From patchwork Wed Jan 14 22:11:42 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 4688 Received: (qmail 16383 invoked by alias); 14 Jan 2015 22:11:55 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 16359 invoked by uid 89); 14 Jan 2015 22:11:53 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.1 required=5.0 tests=AWL, BAYES_00, SPF_HELO_PASS, SPF_PASS, T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Message-ID: <54B6E99E.4030109@redhat.com> Date: Wed, 14 Jan 2015 23:11:42 +0100 From: Florian Weimer User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: GNU C Library Subject: [PATCH] tzset robustness [BZ#17715] This patch removes two different unbounded alloca calls, and also fixes the TZ parser issue identified here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=772705 This is not my preferred approach. I would rather like to sanitize TZ in AT_SECURE mode, so that specifying a file from a non-default TZDIR does not work. However, this alternative approach is a bit involved because the current ld.so setup code is not fit to handle content-dependent environment variable scrubbing. Tested on x86_64-redhat-linux-gnu with no regressions. I also ran the tests in time/ and timezone/ on i386-redhat-linux-gnu, with no failures. The test case from the Debian bug no longer crashes after installing the new glibc version (also on i386). From dcddbd483b8902409f97c778fe9ade2ee533c696 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Wed, 14 Jan 2015 16:33:52 +0100 Subject: [PATCH] Make time zone file parser more robust [BZ #17715] This commit does not yet scrub the TZ environment variable in AT_SECURE mode, as suggested in the bug. 2015-01-14 Florian Weimer [BZ #17715] * time/tzfile.c (__tzfile_read): Check for large values of tzh_ttisstdcnt and tzh_ttisgmtcnt. Reject overlong POSIX time zone specifiers. * time/tzset.c (__tzset_parse_tz): Guard against large time zone specifiers. * timezone/Makefile (tests): Add tst-tzset. (tst-tzset.out): Dependencies on time zone files. (tst-tzset-ENV): Set TZDIR. (testdata/XT%): Copy crafted time zone files. * timezone/README: Mention crafted time zone files. * timezone/testdata/XT1, timezone/testdata/XT2, timezone/testdata/XT3, timezone/testdata/XT4: New time zone test files. * timezone/tst-tzset.c: New test. diff --git a/NEWS b/NEWS index 3bdc96a..4998485 100644 --- a/NEWS +++ b/NEWS @@ -15,9 +15,9 @@ Version 2.21 17501, 17506, 17508, 17522, 17555, 17570, 17571, 17572, 17573, 17574, 17582, 17583, 17584, 17585, 17589, 17594, 17601, 17608, 17616, 17625, 17630, 17633, 17634, 17635, 17647, 17653, 17657, 17658, 17664, 17665, - 17668, 17682, 17717, 17719, 17722, 17723, 17724, 17725, 17732, 17733, - 17744, 17745, 17746, 17747, 17748, 17775, 17777, 17780, 17781, 17782, - 17791, 17793, 17796, 17797, 17803, 17806, 17834 + 17668, 17682, 17715, 17717, 17719, 17722, 17723, 17724, 17725, 17732, + 17733, 17744, 17745, 17746, 17747, 17748, 17775, 17777, 17780, 17781, + 17782, 17791, 17793, 17796, 17797, 17803, 17806, 17834 * Optimized strcpy, stpcpy, strncpy, stpncpy, strcmp, and strncmp implementations for powerpc64/powerpc64le. @@ -48,6 +48,16 @@ Version 2.21 infinite loop if the DNS response contained a PTR record of an unexpected format. +* The time zone file parser has been made more robust against crafted time + zone files, avoiding heap buffer overflows related to the processing of + the tzh_ttisstdcnt and tzh_ttisgmtcnt fields, and a stack overflow due to + large time zone data files. + +* Privileged executables (running SUID/SGID) unset the TZ environment + variable if it refers to a file outside of the default TZDIR directory. + Overly long time zone specifiers in the TZ variable no longer result in + stack overflows and crashes. + * The minimum GCC version that can be used to build this version of the GNU C Library is GCC 4.6. Older GCC versions, and non-GNU compilers, can still be used to compile programs using the GNU C Library. diff --git a/time/tzfile.c b/time/tzfile.c index bcb408f..52897c7 100644 --- a/time/tzfile.c +++ b/time/tzfile.c @@ -200,6 +200,9 @@ __tzfile_read (const char *file, size_t extra, char **extrap) num_isstd = (size_t) decode (tzhead.tzh_ttisstdcnt); num_isgmt = (size_t) decode (tzhead.tzh_ttisgmtcnt); + if (num_isstd > num_types || num_isgmt > num_types) + goto lose; + /* For platforms with 64-bit time_t we use the new format if available. */ if (sizeof (time_t) == 8 && trans_width == 4 && tzhead.tzh_version[0] != '\0') @@ -434,6 +437,10 @@ __tzfile_read (const char *file, size_t extra, char **extrap) goto lose; tzspec_len = st.st_size - off - 1; + if (tzspec_len >= 256) + /* POSIX time zone specifiers are much shorter than 256 + characters. */ + goto lose; char *tzstr = alloca (tzspec_len); if (getc_unlocked (f) != '\n' || (__fread_unlocked (tzstr, 1, tzspec_len - 1, f) diff --git a/time/tzset.c b/time/tzset.c index 8bc7a2e..59fd10d 100644 --- a/time/tzset.c +++ b/time/tzset.c @@ -176,11 +176,14 @@ __tzset_parse_tz (tz) memset (tz_rules, '\0', sizeof tz_rules); tz_rules[0].name = tz_rules[1].name = ""; - /* Get the standard timezone name. */ - char *tzbuf = strdupa (tz); + /* POSIX time zone specifiers are much shorter than 256 characters. */ + char tzbuf[256]; + if (strlen (tz) > sizeof (tzbuf) - 1) + goto out; + /* Get the standard timezone name. */ int consumed; - if (sscanf (tz, "%[A-Za-z]%n", tzbuf, &consumed) != 1) + if (sscanf (tz, "%255[A-Za-z]%n", tzbuf, &consumed) != 1) { /* Check for the quoted version. */ char *wp = tzbuf; @@ -227,7 +230,7 @@ __tzset_parse_tz (tz) /* Get the DST timezone name (if any). */ if (*tz != '\0') { - if (sscanf (tz, "%[A-Za-z]%n", tzbuf, &consumed) != 1) + if (sscanf (tz, "%255[A-Za-z]%n", tzbuf, &consumed) != 1) { /* Check for the quoted version. */ char *wp = tzbuf; diff --git a/timezone/Makefile b/timezone/Makefile index 17424b8..5f18545 100644 --- a/timezone/Makefile +++ b/timezone/Makefile @@ -25,7 +25,7 @@ include ../Makeconfig extra-objs := scheck.o ialloc.o others := zdump zic -tests := test-tz tst-timezone +tests := test-tz tst-timezone tst-tzset # pacificnew doesn't compile; if it is to be used, it should be included in # northamerica. @@ -90,9 +90,11 @@ $(objpfx)tst-timezone.out: $(addprefix $(testdata)/, \ Australia/Melbourne \ America/Sao_Paulo Asia/Tokyo \ Europe/London) +$(objpfx)tst-tzset.out: $(addprefix $(testdata)/XT, 1 2 3 4) test-tz-ENV = TZDIR=$(testdata) tst-timezone-ENV = TZDIR=$(testdata) +tst-tzset-ENV = TZDIR=$(testdata) # Note this must come second in the deps list for $(built-program-cmd) to work. zic-deps = $(objpfx)zic $(leapseconds) yearistype @@ -114,6 +116,8 @@ $(testdata)/America/Sao_Paulo: southamerica $(zic-deps) $(testdata)/Asia/Tokyo: asia $(zic-deps) $(build-testdata) +$(testdata)/XT%: testdata/XT% + cp $< $@ $(objpfx)tzselect: tzselect.ksh $(common-objpfx)config.make sed -e 's|/bin/bash|$(BASH)|' \ diff --git a/timezone/README b/timezone/README index 7a5e31c..2268f8e 100644 --- a/timezone/README +++ b/timezone/README @@ -15,3 +15,6 @@ version of the tzcode and tzdata packages. These packages may be found at ftp://ftp.iana.org/tz/releases/. Commentary should be addressed to tz@iana.org. + +The subdirectory testdata contains manually edited data files for +regression testing purposes. diff --git a/timezone/testdata/XT1 b/timezone/testdata/XT1 new file mode 100644 index 0000000000000000000000000000000000000000..67d7ee0ba59389b4aaea0bdce15ff6bf7056c5ef GIT binary patch literal 127 zcmWHE%1kq2Kn4GS04TzYB+3Y6vq1O}A%;Lk2w{C7Jz#x5AR1vL!~iZJWxxdhA3F~_ literal 0 HcmV?d00001 diff --git a/timezone/testdata/XT2 b/timezone/testdata/XT2 new file mode 100644 index 0000000000000000000000000000000000000000..069189e34998662d526b3645891d515a31fd6495 GIT binary patch literal 127 wcmWHE%1kq2zyQqufdEOA5y)nN@FPM%>O%. */ + +#define _GNU_SOURCE 1 + +#include +#include +#include +#include +#include +#include + +/* Returns the name of a large TZ file. */ +static char * +create_tz_file (void) +{ + char * path = strdup ("/tmp/tst-tzset-XXXXXX"); + if (path == NULL) + { + printf ("strdup failed: %m\n"); + exit (1); + } + int fd = mkstemp (path); + if (fd < 0) + { + printf ("mkstemp failed: %m\n"); + exit (1); + } + static const char data[] = { + 0x54, 0x5a, 0x69, 0x66, 0x32, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, + 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, + 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x58, 0x54, 0x47, 0x00, 0x00, 0x00, + 0x54, 0x5a, 0x69, 0x66, 0x32, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, + 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, + 0x00, 0x00, 0x00, 0x04, 0xf8, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x58, 0x54, 0x47, 0x00, 0x00, + 0x00, 0x0a, 0x58, 0x54, 0x47, 0x30, 0x0a + }; + ssize_t ret = write (fd, data, sizeof (data)); + if (ret < 0) + { + printf ("write failed: %m\n"); + exit (1); + } + if ((size_t) ret != sizeof (data)) + { + printf ("Short write\n"); + exit (1); + } + if (lseek (fd, 64 * 1024 * 1024, SEEK_CUR) < 0) + { + printf ("lseek failed: %m\n"); + exit (1); + } + if (write (fd, "", 1) != 1) + { + printf ("Single-byte write failed\n"); + exit (1); + } + if (close (fd) != 0) + { + printf ("close failed: %m\n"); + exit (1); + } + return path; +} + +static int +do_test (void) +{ + int errors = 0; + for (int i = 1; i <= 4; ++i) + { + char tz[16]; + snprintf (tz, sizeof (tz), "XT%d", i); + if (setenv ("TZ", tz, 1) < 0) + { + printf ("setenv failed: %m\n"); + return 1; + } + tzset (); + if (strcmp (tzname[0], tz) == 0) + { + printf ("Unexpected success for %s\n", tz); + ++errors; + } + } + + /* Large TZ file. */ + { + char *path = create_tz_file (); + if (setenv ("TZ", path, 1) < 0) + { + printf ("setenv failed: %m\n"); + return 1; + } + /* This will succeed on 64-bit architectures, and fail on 32-bit + architectures. It used to crash on 32-bit. */ + tzset (); + unlink (path); + free (path); + } + + /* Large TZ variable. */ + { + size_t length = 64 * 1024 * 1024; + char *value = malloc (length + 1); + if (value == NULL) + { + puts ("malloc failed: %m"); + return 1; + } + value[length] = '\0'; + memset (value, ' ', length); + value[0] = 'U'; + value[1] = 'T'; + value[2] = 'C'; + if (setenv ("TZ", value, 1) < 0) + { + printf ("setenv failed: %m\n"); + return 1; + } + tzset (); + } + + return errors > 0; +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" -- 2.1.0