Potentially missing object files in libc.a... #5
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mikpe
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Dec 13, 2021
- use the provided __res_state() method instead of direct access to struct __res_state pointer &_res/*__resp - change the __UCLIBC_HAS_TLS__ protected __res_state() implementation to the one where the comment 'When threaded, _res may be a per-thread variable.' indicates this should be used with threads/TLS enabled Fixes the following segfaults with buildroot raspberrypi3_64_defconfig (uclibc, -Os, Note: runs fine using the raspberrypi3_defconfig): $ /usr/sbin/ntpd -n -d 1970-01-01T00:01:49 ntpd[249]: INIT: ntpd ntpsec-1.2.0 2021-11-03T20:39:50Z: Starting 1970-01-01T00:01:49 ntpd[249]: INIT: Command line: /usr/sbin/ntpd -n -d 1970-01-01T00:01:49 ntpd[249]: INIT: precision = 7.240 usec (-17) 1970-01-01T00:01:49 ntpd[249]: INIT: successfully locked into RAM 1970-01-01T00:01:49 ntpd[249]: CONFIG: readconfig: parsing file: /etc/ntp.conf 1970-01-01T00:01:49 ntpd[249]: CONFIG: restrict nopeer ignored 1970-01-01T00:01:49 ntpd[249]: INIT: Using SO_TIMESTAMPNS 1970-01-01T00:01:49 ntpd[249]: IO: Listen and drop on 0 v6wildcard [::]:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen and drop on 1 v4wildcard 0.0.0.0:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 2 lo 127.0.0.1:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 3 eth0 172.16.0.30:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 4 lo [::1]:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 5 eth0 [fe80::ba27:ebff:fea6:340%2]:123 1970-01-01T00:01:49 ntpd[249]: IO: Listening on routing socket on fd #22 for interface updates 1970-01-01T00:01:50 ntpd[249]: SYNC: Found 10 servers, suggest minsane at least 3 1970-01-01T00:01:50 ntpd[249]: INIT: MRU 10922 entries, 13 hash bits, 65536 bytes 1970-01-01T00:01:50 ntpd[249]: statistics directory /var/NTP/ does not exist or is unwriteable, error No such file or directory 1970-01-01T00:01:51 ntpd[249]: DNS: dns_probe: 0.pool.ntp.org, cast_flags:8, flags:101 Segmentation fault (core dumped) $ ./host/bin/aarch64-buildroot-linux-uclibc-gdb ./build/ntpsec-1_2_0/build/main/ntpd/ntpd core Core was generated by `/usr/sbin/ntpd -n -d'. Program terminated with signal SIGSEGV, Segmentation fault. (gdb) where #0 0x0000007f8ff1f150 in res_sync_func () at libc/inet/resolv.c:3356 wbx-github#1 0x0000007f8ff1c468 in __open_nameservers () at libc/inet/resolv.c:949 wbx-github#2 0x0000007f8ff1b498 in __dns_lookup (name=0x55943c67f0 "0.pool.ntp.org", type=1, outpacket=0x7f8fe91c48, a=0x7f8fe91c08) at libc/inet/resolv.c:1134 wbx-github#3 0x0000007f8ff1d744 in __GI_gethostbyname_r ( name=0x55943c67f0 "0.pool.ntp.org", result_buf=0x7f8fe92628, buf=0x7f8fe91d90 "", buflen=992, result=0x7f8fe92670, h_errnop=0x7f8fe92668) at libc/inet/resolv.c:1966 wbx-github#4 0x0000007f8ff1d9a0 in __GI_gethostbyname2_r ( name=0x55943c67f0 "0.pool.ntp.org", family=2, result_buf=0x7f8fe92628, buf=0x7f8fe91d70 "0.pool.ntp.org", buflen=1024, result=0x7f8fe92670, h_errnop=0x7f8fe92668) at libc/inet/resolv.c:2065 wbx-github#5 0x0000007f8ff16924 in gaih_inet (name=0x55943c67f0 "0.pool.ntp.org", service=0x7f8fe92828, req=0x7f8fe92890, pai=0x7f8fe92838) at libc/inet/getaddrinfo.c:596 wbx-github#6 0x0000007f8ff17624 in __GI_getaddrinfo ( name=0x55943c67f0 "0.pool.ntp.org", service=0x5582eb8acd "\377H\213D$\bL\211\367H\213\260\270", hints=0x7f8fe92890, pai=0x5582ee1bf8) at libc/inet/getaddrinfo.c:957 wbx-github#7 0x0000005582ea60f4 in _start () (gdb) p _res $1 = {options = 0, nsaddr_list = {{sin_family = 0, sin_port = 0, sin_addr = { s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}, { sin_family = 0, sin_port = 0, sin_addr = {s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}, {sin_family = 0, sin_port = 0, sin_addr = {s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}}, dnsrch = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, nscount = 0 '\000', ndots = 0 '\000', retrans = 0 '\000', retry = 0 '\000', defdname = '\000' <repeats 255 times>, nsort = 0 '\000', pfcode = 0, id = 0, res_h_errno = 0, sort_list = {{addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}}, _u = { _ext = {nsaddrs = {0x0, 0x0, 0x0}, nscount = 0 '\000', nstimes = {0, 0, 0}, nssocks = {0, 0, 0}, nscount6 = 0, nsinit = 0}}} (gdb) p &_res $2 = (struct __res_state *) 0x7f8ff8fd98 <_res> (gdb) p rp $3 = (struct __res_state *) 0x7fffffffff And the following uclibc code at libc/inet/resolv.c:3356: 3345 static void res_sync_func(void) 3346 { 3347 struct __res_state *rp = &(_res); 3348 int n; 3349 3350 /* If we didn't get malloc failure earlier... */ 3351 if (__nameserver != (void*) &__local_nameserver) { 3352 /* TODO: 3353 * if (__nameservers < rp->nscount) - try to grow __nameserver[]? 3354 */ 3355 #ifdef __UCLIBC_HAS_IPV6__ 3356 if (__nameservers > rp->_u._ext.nscount) 3357 __nameservers = rp->_u._ext.nscount; 3358 n = __nameservers; The special thing about ntpsec is the DNS lookup in an extra thread and/or the call to res_init(), see ntpsec-1_2_0/ntpd/ntp_dns.c: 69 msyslog(LOG_INFO, "DNS: dns_probe: %s, cast_flags:%x, flags:%x%s", 70 hostname, pp->cast_flags, pp->cfg.flags, busy); 71 if (NULL != active) /* normally redundant */ 72 return false; 73 74 active = pp; 75 76 sigfillset(&block_mask); 77 pthread_sigmask(SIG_BLOCK, &block_mask, &saved_sig_mask); 78 rc = pthread_create(&worker, NULL, dns_lookup, pp); and 165 static void* dns_lookup(void* arg) 166 { 167 struct peer *pp = (struct peer *) arg; 168 struct addrinfo hints; 169 170 #ifdef HAVE_SECCOMP_H 171 setup_SIGSYS_trap(); /* enable trap for this thread */ 172 #endif 173 174 #ifdef HAVE_RES_INIT 175 /* Reload DNS servers from /etc/resolv.conf in case DHCP has updated it. 176 * We only need to do this occasionally, but it's not expensive 177 * and simpler to do it every time than it is to figure out when 178 * to do it. 179 * This res_init() covers NTS too. 180 */ 181 res_init(); 182 #endif 183 184 if (pp->cfg.flags & FLAG_NTS) { 185 #ifndef DISABLE_NTS 186 nts_probe(pp); 187 #endif 188 } else { 189 ZERO(hints); 190 hints.ai_protocol = IPPROTO_UDP; 191 hints.ai_socktype = SOCK_DGRAM; 192 hints.ai_family = AF(&pp->srcadr); 193 gai_rc = getaddrinfo(pp->hostname, NTP_PORTA, &hints, &answer); 194 } $ /usr/lib/uclibc-ng-test/test/inet/tst-res Segmentation fault (core dumped) $ ./host/bin/aarch64-buildroot-linux-uclibc-gdb ./build/uclibc-ng-test-0844445e7358eb10e716155b55b0fb23e88d644a/test/inet/tst-res core Core was generated by `/usr/lib/uclibc-ng-test/test/inet/tst-res'. Program terminated with signal SIGSEGV, Segmentation fault. (gdb) where #0 __GI___res_init () at libc/inet/resolv.c:3514 wbx-github#1 0x0000005591e507e4 in main (argc=<optimized out>, argv=<optimized out>) at tst-res.c:20 First reported here: https://lore.kernel.org/buildroot/[email protected]/ https://www.mail-archive.com/[email protected]/msg01085.html Signed-off-by: Peter Seiderer <[email protected]>
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I'm not sure if this is a real problem or just my misunderstanding, but I noticed what I believe should be object files in the libc.a archive. They get compiled but do not appear to get into the archive. There are 45 of them. They are listed below. The configuration I used was with the default values, except for:
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