After I updated my Centos to 7.5.1804, my virtual machine crashed when I connected with vnc password.
1. My problem：
Here what I tested:
(1). started a guest with : qemu-system-x86_64 -m 2048 test.img -vnc
0.0.0.0:7,password -monitor stdio
(2). change password to 1234567.
(3). connected with VncViewer
Here was the output:
# qemu-system-x86_64 -m 2048 test.img -vnc
0.0.0.0:3,password -monitor stdio
QEMU 2.5.1.1 monitor - type 'help' for more information
(qemu) change vnc password 12345678
(qemu) Segmentation fault
I debugged with gdb and got:
(qemu) change vnc password 12345678
(qemu)
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff528cc80 in pthread_mutex_lock () from /lib64/libpthread.so.0
(gdb) bt
#0 0x00007ffff528cc80 in pthread_mutex_lock () from /lib64/libpthread.so.0
#1 0x0000555555a97f4a in qemu_mutex_lock (mutex=0x0) at util/qemu-thread-posix.c:73
#2 0x0000555555a5cce3 in qcrypto_gcrypt_mutex_lock (priv=0x7ffff6e90ca0) at crypto/init.c:97
#3 0x00007ffff6c217c5 in mutex_init () from /lib64/libgcrypt.so.11
#4 0x00007ffff6c21baa in _gcry_ath_mutex_lock () from /lib64/libgcrypt.so.11
#5 0x00007ffff6c5ad20 in lock_pool () from /lib64/libgcrypt.so.11
#6 0x00007ffff6c5be2e in _gcry_rngcsprng_fast_poll () from /lib64/libgcrypt.so.11
#7 0x00007ffff6c23d4d in _gcry_cipher_open () from /lib64/libgcrypt.so.11
#8 0x0000555555a60251 in qcrypto_cipher_new (alg=QCRYPTO_CIPHER_ALG_DES_RFB, mode=QCRYPTO_CIPHER_MODE_ECB, key=0x7fffffffdf30 "12345678\020", nkey=8, errp=0x7fffffffdf08) at ./crypto/cipher-gcrypt.c:97
#9 0x00005555559d8912 in protocol_client_auth_vnc (vs=0x5555565b5660, data="" "\036\352\"s٘\373\345<ܯ\210L\b;$\220\300\246WUU", len=16) at ui/vnc.c:2551
#10 0x00005555559d60b5 in vnc_client_read (opaque=0x5555565b5660) at ui/vnc.c:1564
#11 0x0000555555a046a7 in aio_dispatch (ctx=0x555556508790) at aio-posix.c:326
#12 0x00005555559f4166 in aio_ctx_dispatch (source=0x555556508790, callback=0x0, user_data=0x0) at async.c:231
#13 0x00007ffff5f10969 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#14 0x0000555555a026e7 in glib_pollfds_poll () at main-loop.c:211
#15 0x0000555555a027c4 in os_host_main_loop_wait (timeout=54752182) at main-loop.c:256
#16 0x0000555555a02874 in main_loop_wait (nonblocking=0) at main-loop.c:504
#17 0x00005555558251c1 in main_loop () at vl.c:1923
#18 0x000055555582cbe5 in main (argc=8, argv=0x7fffffffe558, envp=0x7fffffffe5a0) at vl.c:4699
2. Other Infomation
(1). Version of qemu:
QEMU emulator version 2.5.1.1, Copyright (c) 2003-2008 Fabrice Bellard
(2). kernel and os：
kernel : 4.16.3-1.el7.elrepo.x86_64
os: CentOS Linux release 7.5.1804 (Core)
(3). I had try /usr/libexec/qemu-kvm(qemu-kvm-1.5.3-156.el7_5.5) and qemu 2.11, both of them worked fine.
(4). Has no problem witout vnc password.
(5). I update my host with yum update.
(6). Everything work find before update.
3. My Question
For some reasons I have to use qemu 2.5.11 and update Centos.
(1) What causes this problem and how can I solve it ?
Looking forward to your reply.