Bug#882586: libc6-dev:amd64: pthread_rwlock_unlock segfaults in statically linked executable

[g1 <g1pi@libero.it>]

Package: libc6-dev
Version: 2.24-11+deb9u1
Severity: important

A minimal program that exercises R/W locks crashes when linked statically:

$ cat test-rwlock.c
#include <pthread.h>
int main() {
    pthread_rwlock_t rw;
    if (pthread_rwlock_init(&rw, NULL)) return -1;
    if (pthread_rwlock_wrlock(&rw))     return -2;
    if (pthread_rwlock_unlock(&rw))     return -3;
    if (pthread_rwlock_destroy(&rw))    return -4;
    return 0;
}

$ cc -pthread         -O0 -g test-rwlock.c ; ./a.out ; echo $?
0

$ cc -pthread -static -O0 -g test-rwlock.c ; ./a.out ; echo $?
Illegal instruction
132

Most likely, the problem is not in pthread_rwlock_unlock, but in
pthread_rwlock_wrlock: gdb shows that when the latter returns, 
    rw.__data.__writer == pid_of_the_process
in the dynamic case, and 
    rw.__data.__writer == 0 
in the static case.

Best regards,
	g.



-- System Information:
Debian Release: 9.1
  APT prefers stable-debug
  APT policy: (500, 'stable-debug'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: sysvinit (via /sbin/init)

Versions of packages libc6-dev:amd64 depends on:
ii  libc-dev-bin    2.24-11+deb9u1
ii  libc6           2.24-11+deb9u1
ii  linux-libc-dev  4.9.51-1

libc6-dev:amd64 recommends no packages.

Versions of packages libc6-dev:amd64 suggests:
ii  glibc-doc     2.24-11+deb9u1
ii  manpages-dev  4.10-2

-- no debconf information