From: "Pierre A. Humblet" <Pierre.Humblet@alum.mit.edu>
To: cygwin@cygwin.com
Subject: Re: Exim & cygwin-2.6.0-1 (x86) fatal Signal 6 on start
Date: Wed, 04 Jan 2017 00:36:00 -0000 [thread overview]
Message-ID: <586C438A.1060206@alum.mit.edu> (raw)
In-Reply-To: <31f6707c-6600-c0a3-daff-c0825dcf4f04@rosshemail.com>
On 9/12/2016 8:26 AM, Ross Hemingway wrote:
> Update to cygwin-2.6.0-1. Exim has a fatal start error - exim: PID
> 3756: service `exim' failed: signal 6 raised.
>
> Rolled back to cygwin-2.5.2-1, problem averted.
>
Sorry for the very long delay in answering.
The debugging below was done from a non-privileged account, and the
setuid32() should thus fail, but the program should not abort.
It aborts in the call to "free (privs)".
"privs" are obtained by get_priv_list().
When the target user is SYSTEM, get_priv_list() returns
(PTOKEN_PRIVILEGES) &sys_privs;
where "sys_privs" is a constant structure that cannot be freed.
Pierre
Breakpoint 2, setuid32 (uid=18) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/syscalls.cc:3426
3426 {
(gdb) c
Continuing.
Breakpoint 3, create_token (usersid=..., new_groups=...) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/sec_auth.cc:856
856 {
(gdb) b 978
Breakpoint 4 at 0x180107e98: file
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/sec_auth.cc,
line 978.
(gdb) c
Continuing.
Breakpoint 4, create_token (usersid=..., new_groups=...) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/sec_auth.cc:978
978 if (status)
(gdb) n
979 __seterrno_from_nt_status (status);
(gdb) n
993 pop_self_privilege ();
(gdb) n
994 if (token != INVALID_HANDLE_VALUE)
(gdb) n
996 if (privs)
(gdb) n
997 free (privs);
(gdb) s
free (p=0x180247e40 <sys_privs>) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/malloc_wrapper.cc:36
36 malloc_printf ("(%p), called by %p", p, caller_return_address ());
(gdb) n
35 {
(gdb) n
36 malloc_printf ("(%p), called by %p", p, caller_return_address ());
(gdb) n
37 if (!use_internal)
(gdb) n
41 __malloc_lock ();
(gdb) n
42 dlfree (p);
(gdb) s
dlfree (mem=mem@entry=0x180247e40 <sys_privs>) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/malloc.cc:4688
4688 if (mem != 0) {
(gdb) p mem
$8 = (void *) 0x180247e40 <sys_privs>
(gdb) n
4701 if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {
(gdb) n
4689 mchunkptr p = mem2chunk(mem);
(gdb) n
4701 if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {
(gdb) n
4780 USAGE_ERROR_ACTION(fm, p);
(gdb) s
abort () at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/signal.cc:364
364 _my_tls.incyg++;
(gdb) n
365 sig_dispatch_pending ();
(gdb) s
364 _my_tls.incyg++;
(gdb) s
365 sig_dispatch_pending ();
(gdb) s
sig_dispatch_pending (fast=fast@entry=false) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/sigproc.cc:438
438 if (sigq.pending () && &_my_tls != _sig_tls)
(gdb) s
pending_signals::pending (this=0x180212220 <sigq>, this=0x180212220
<sigq>) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/sigproc.cc:77
77 bool pending () {retry = true; return !!start.next;}
(gdb) s
sig_dispatch_pending (fast=fast@entry=false) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/sigproc.cc:438
438 if (sigq.pending () && &_my_tls != _sig_tls)
(gdb) s
440 }
(gdb) s
abort () at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/signal.cc:369
369 sigdelset (&sig_mask, SIGABRT);
(gdb) s
368 sigfillset (&sig_mask);
(gdb) s
sigfillset (set=0xffff9c68) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/signal.cc:506
506 *set = ~((sigset_t) 0);
(gdb) s
abort () at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/signal.cc:369
369 sigdelset (&sig_mask, SIGABRT);
(gdb) s
sigdelset (set=0xffff9c68, sig=6) at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/signal.cc:466
466 {
(gdb) s
468 if (sig <= 0 || sig >= NSIG)
(gdb) s
466 {
(gdb) s
468 if (sig <= 0 || sig >= NSIG)
(gdb) s
475 *set &= ~SIGTOMASK (sig);
(gdb) s
477 }
(gdb) s
abort () at
/ext/build/mknetrel/src/cygwin-snapshot-20161214-1/winsup/cygwin/signal.cc:370
370 set_signal_mask (_my_tls.sigmask, sig_mask);
--
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next prev parent reply other threads:[~2017-01-04 0:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-12 12:26 Ross Hemingway
2017-01-04 0:36 ` Pierre A. Humblet [this message]
2017-01-09 13:04 ` Corinna Vinschen
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