From: Peter Eriksson <pen@lysator.liu.se>
To: linux-nfs@vger.kernel.org
Subject: [Bug report] NULL-pointer dereference in gssd (nfs-utils version 1.3.4 & 2.3.3)
Date: Fri, 1 Mar 2019 13:25:40 +0100 [thread overview]
Message-ID: <77C72E28-D137-408E-834B-623341F21BB3@lysator.liu.se> (raw)
I’m seeing Segmentation Faults in gssd from nfs-utils 1.3.4 and 2.3.3 when running it on a machine running CentOS 7.6.1810 / kernel 3.10.0-957.5.1.el7.x86_64 that uses GSSAPI quite a bit (a Linux machine doing validation checks of our fileserver - runs a list of SMB/NFS/LDAP/Kerberos check every minute 24/7). We compiled our own version since the version that CentOS delivers (1.3.0) also crashed (unsure if it is the same bug there though).
# gdb ./gssd
(gdb) run -f -v
...
[New Thread 0x7fffef7fe700 (LWP 24902)]
Error doing scandir on directory '/run/user/11189': No such file or directory
[Thread 0x7fffef7fe700 (LWP 24902) exited]
[New Thread 0x7fffeffff700 (LWP 24904)]
Error doing scandir on directory '/run/user/11189': No such file or directory
[Thread 0x7fffeffff700 (LWP 24904) exited]
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff4cec700 (LWP 24448)]
create_auth_rpc_client (clp=clp@entry=0x621590, tgtname=tgtname@entry=0x0,
clnt_return=clnt_return@entry=0x7ffff4cebd48,
auth_return=auth_return@entry=0x7ffff4cebcd0, uid=uid@entry=0,
authtype=authtype@entry=0, cred=cred@entry=0x0) at gssd_proc.c:352
352 if ((strcmp(clp->protocol, "udp")) == 0)
Missing separate debuginfos, use: debuginfo-install glibc-2.17-260.el7_6.3.x86_64 gssproxy-0.7.0-21.el7.x86_64 keyutils-libs-1.5.8-3.el7.x86_64 krb5-libs-1.15.1-37.el7_6.x86_64 libcom_err-1.42.9-13.el7.x86_64 libevent-2.0.21-4.el7.x86_64 libselinux-2.5-14.1.el7.x86_64 libtirpc-0.2.4-0.15.el7.x86_64 pcre-8.32-17.el7.x86_64
(gdb) where
#0 create_auth_rpc_client (clp=clp@entry=0x621590, tgtname=tgtname@entry=0x0,
clnt_return=clnt_return@entry=0x7ffff4cebd48,
auth_return=auth_return@entry=0x7ffff4cebcd0, uid=uid@entry=0,
authtype=authtype@entry=0, cred=cred@entry=0x0) at gssd_proc.c:352
#1 0x0000000000406d21 in krb5_use_machine_creds (rpc_clnt=0x7ffff4cebd48,
service=0x6293c0 "*", tgtname=0x0, srchost=0x0, uid=0, clp=0x621590)
at gssd_proc.c:569
#2 process_krb5_upcall (clp=clp@entry=0x621590, uid=uid@entry=0, fd=13,
srchost=srchost@entry=0x0, tgtname=tgtname@entry=0x0,
service=service@entry=0x6293c0 "*") at gssd_proc.c:657
#3 0x000000000040759c in handle_gssd_upcall (info=0x6293a0) at gssd_proc.c:819
#4 0x00007ffff6de6dd5 in start_thread () from /lib64/libpthread.so.0
#5 0x00007ffff68f6ead in clone () from /lib64/libc.so.6
(gdb) frame 0
#0 create_auth_rpc_client (clp=clp@entry=0x621590, tgtname=tgtname@entry=0x0,
clnt_return=clnt_return@entry=0x7ffff4cebd48,
auth_return=auth_return@entry=0x7ffff4cebcd0, uid=uid@entry=0,
authtype=authtype@entry=0, cred=cred@entry=0x0) at gssd_proc.c:352
352 if ((strcmp(clp->protocol, "udp")) == 0)
(gdb) list
347
348 printerr(2, "creating %s client for server %s\n", clp->protocol,
349 clp->servername);
350
351 protocol = IPPROTO_TCP;
352 if ((strcmp(clp->protocol, "udp")) == 0)
353 protocol = IPPROTO_UDP;
354
355 switch (addr->sa_family) {
356 case AF_INET:
(gdb) print clp
$1 = (struct clnt_info *) 0x621590
(gdb) print clp->protocol
$2 = 0x0
(gdb) print *clp
$3 = {list = {tqe_next = 0x0, tqe_prev = 0xffffffff}, wd = 0, scanned = false,
name = 0x0, relpath = 0x0, servicename = 0x0, servername = 0x0, prog = 0,
vers = 0, protocol = 0x0, krb5_fd = 0, krb5_ev = {ev_active_next = {
tqe_next = 0x0, tqe_prev = 0x0}, ev_next = {tqe_next = 0x0,
tqe_prev = 0x0}, ev_timeout_pos = {ev_next_with_common_timeout = {
tqe_next = 0x0, tqe_prev = 0x0}, min_heap_idx = 0}, ev_fd = 0,
ev_base = 0x0, _ev = {ev_io = {ev_io_next = {tqe_next = 0x0,
tqe_prev = 0x0}, ev_timeout = {tv_sec = 0, tv_usec = 0}},
ev_signal = {ev_signal_next = {tqe_next = 0x0, tqe_prev = 0x0},
ev_ncalls = 0, ev_pncalls = 0x0}}, ev_events = 0, ev_res = 0,
ev_flags = 0, ev_pri = 0 '\000', ev_closure = 0 '\000', ev_timeout = {
tv_sec = 0, tv_usec = 0}, ev_callback = 0x0, ev_arg = 0x0}, gssd_fd = 0,
gssd_ev = {ev_active_next = {tqe_next = 0x0, tqe_prev = 0x0}, ev_next = {
tqe_next = 0x0, tqe_prev = 0x0}, ev_timeout_pos = {
ev_next_with_common_timeout = {tqe_next = 0x0, tqe_prev = 0x0},
min_heap_idx = 0}, ev_fd = 496, ev_base = 0x70, _ev = {ev_io = {
ev_io_next = {tqe_next = 0x0, tqe_prev = 0x7f3865333232},
ev_timeout = {tv_sec = 0, tv_usec = 273}}, ev_signal = {
ev_signal_next = {tqe_next = 0x0, tqe_prev = 0x7f3865333232},
ev_ncalls = 0, ev_pncalls = 0x111}}, ev_events = -1864,
ev_res = -2373, ev_flags = 32767, ev_pri = 0 '\000',
ev_closure = 0 '\000', ev_timeout = {tv_sec = 140737332902072,
tv_usec = 4294977170}, ev_callback = 0x6218c4, ev_arg = 0x240}, addr = {
---Type <return> to continue, or q <return> to quit---
ss_family = 32,
__ss_padding = "\000\000\000\000\000\000\260\020b\000\000\000\000\000\270\367\273\366\377\177\000\000`\002\000\000\000\000\000\000\301\000\000\000\000\000\000\000\360\027b\000\000\000\000\000\000\214b", '\000' <repeats 13 times>, "\241\000\000\000\000\000\000\000\200\021b\000\000\000\000\000H\370\273\366\377\177", '\000' <repeats 26 times>, "q\000\000\000\000\000\000", __ss_align = 6427008}}
(gdb) frame 1
#1 0x0000000000406d21 in krb5_use_machine_creds (rpc_clnt=0x7ffff4cebd48,
service=0x6293c0 "*", tgtname=0x0, srchost=0x0, uid=0, clp=0x621590)
at gssd_proc.c:569
569 if ((create_auth_rpc_client(clp, tgtname, rpc_clnt,
(gdb) list
564 printerr(1, "WARNING: gss_krb5_ccache_name "
565 "with name '%s' failed (%s)\n",
566 *ccname, error_message(min_stat));
567 continue;
568 }
569 if ((create_auth_rpc_client(clp, tgtname, rpc_clnt,
570 &auth, uid,
571 AUTHTYPE_KRB5,
572 GSS_C_NO_CREDENTIAL)) == 0) {
573 /* Success! */
(gdb) print tgtname
$6 = 0x0
(gdb) print rpc_clnt
$7 = (CLIENT **) 0x7ffff4cebd48
(gdb) print *rpc_clnt
$8 = (CLIENT *) 0x0
(gdb) frame 2
#2 process_krb5_upcall (clp=clp@entry=0x621590, uid=uid@entry=0, fd=13,
srchost=srchost@entry=0x0, tgtname=tgtname@entry=0x0,
service=service@entry=0x6293c0 "*") at gssd_proc.c:657
657 auth = krb5_use_machine_creds(clp, uid, srchost, tgtname,
(gdb) list
652 goto out_return_error;
653 }
654 if (auth == NULL) {
655 if (uid == 0 && (root_uses_machine_creds == 1 ||
656 service != NULL)) {
657 auth = krb5_use_machine_creds(clp, uid, srchost, tgtname,
658 service, &rpc_clnt);
659 if (auth == NULL)
660 goto out_return_error;
661 } else {
(gdb) print uid
$9 = 0
(gdb) print srchost
$10 = 0x0
(gdb) print tgtname
$11 = 0x0
Exactly what is causing this event to happen is unclear (a lot of automated checks are running, but they run well for a couple of hours before this crash occur).
Please let me know if there is some other information someone might need to fix this bug… (I’m going to add sanity checks to the code in order to try to mitigate the crash and instead fail in a more “nice” way).
- Peter
next reply other threads:[~2019-03-01 12:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-01 12:25 Peter Eriksson [this message]
2019-03-07 15:52 ` [Patch] NULL-pointer dereference in gssd (nfs-utils version 1.3.0, 1.3.4 & 2.3.3) Peter Eriksson
2019-03-11 18:25 ` Steve Dickson
2019-03-14 7:51 ` Peter Eriksson
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