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From: Jim Schneider <jim DOT schneider AT dataflux DOT com>
To: "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Date: Wed, 30 Nov 2011 15:33:28 -0500
Subject: 1.7.9-1 dll::init() still causing STATUS_ACCESS_VIOLATION errors
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I updated today to 1.7.9-1 from an earlier install.   Now, bash produces a series of dozens of exception lines like the following:

214713567 [main] bash 5368 exception::handle: Exception: STATUS_ACCESS_VIOLATION
214714267 [main] bash 5368 open_stackdumpfile: Dumping stack trace to bash.exe.stackdump

The contents of bash.exe.stackdump are:

Exception: STATUS_ACCESS_VIOLATION at eip=6102048B
eax=00C40308 ebx=6124545C ecx=75110F81 edx=003C51F8 esi=00000000 edi=0028F9F4
ebp=61020C00 esp=0028C7C4 program=C:\cygwin\bin\bash.exe, pid 1928, thread main
cs=0023 ds=002B es=002B fs=0053 gs=002B ss=002B
Stack trace:
Frame     Function  Args
End of stack trace

The address 6102048B is associated with line 82 of winsup/cygwin/dll_init.cc, which is in dll::init():

/* Initialize an individual DLL */
int
dll::init ()
{
  int ret = 1;

  /* This should be a no-op.  Why didn't we just import this variable? */
  if (!p.envptr)
    p.envptr = &__cygwin_environ;
  else
    *(p.envptr) = __cygwin_environ;		/* This is line 82 */

  /* Don't run constructors or the "main" if we've forked. */
  if (!in_forkee)
    {
      /* global contructors */
      p.run_ctors ();

      /* entry point of dll (use main of per_process with null args...) */
      if (p.main)
        ret = p.main (0, 0, 0);
    }

  return ret;
}

The pointer p.envptr is tested before an attempt is made to use it, so it looks like it is getting garbage.  Disassembling the function dll::init shows that the edx register is being used to hold the address.  It's holding 003C51F8, just short of 240K before the base address of bash.

If I manage to run it down, I'll send a patch.


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