gdb 7.3.50-2 crash

gdb 7.3.50-2 crash

[Ken Brown]

gdb 7.3.50-2 crashes with a segfault if a file is loaded and the 
following two command lines are sent:

server interpreter mi "-file-list-exec-source-files"
server list

To reproduce, run `gdb t.exe' and then type in those two lines.  Here 
t.exe can be any executable, I think.  I tried several and got the crash 
every time.  Specifically, it happens with a standard "Hello, world!" 
program:

$ cat t.c
#include <stdio.h>
int main(void)
{
  printf("Hello World\n");
  return 0;
}

This crash explains the problem reported in

   http://cygwin.com/ml/cygwin/2011-09/msg00172.html

Ken

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Re: gdb 7.3.50-2 crash

[Ken Brown]

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On 10/16/2011 7:01 AM, Ken Brown wrote:
> gdb 7.3.50-2 crashes with a segfault if a file is loaded and the
> following two command lines are sent:
>
> server interpreter mi "-file-list-exec-source-files"
> server list

I don't know if it helps, but I've modified the STC from 
http://cygwin.com/ml/cygwin/2011-10/msg00472.html to apply to the 
present problem.  I had to uncomment the sleep (1) to get it to run 
properly on my Linux system.  I also made the STC run "gdb --annotate=3" 
even though the crash occurs with just "gdb", because that's how gdb is 
run by emacs in the situation that led to this bug report.

The STC assumes that you have hello.exe in the current directory.

$ cat > hello.c << EOF
#include <stdio.h>

int
main ()
{
  printf("Hello, world!\n");
  return 0;
}
EOF

$ gcc -g -o hello hello.c

Ken

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pty.h>
#include <string.h>
#include <sys/wait.h>

void get_output (int fd);

int
main (int argc, const char **argv) 
{
  int master;
  pid_t pid;

  if ((pid = forkpty (&master, NULL, NULL, NULL)) < 0)
    {
      perror ("forkpty");
      exit (1);
    }
  /* child */
  if (pid == 0) 
    {
      const char *av[100];
      int i = 0;
#ifdef STRACE_GDB
      av[i++] = "strace";
      av[i++] = "-o";
      av[i++] = "/tmp/strace.out";
#ifdef __CYGWIN__
      av[i++] = "--mask=all+paranoid";
#endif
#endif
      av[i++] = argv[1] ?: "gdb";
      fprintf (stderr, "*** using %s\n", av[0]);
      av[i++] = "--annotate=3";
      av[i++] = "hello.exe";
      av[i] = NULL;
      execvp (av[0], (char * const *) av);
      /* shouldn't get here */
      exit (1);
    }
  /* parent */
  const char *input[20];

  int i = 0;
  input[i++] = "server interpreter mi \"-file-list-exec-source-files\"\n";
  input[i++] = "server list\n";
  input[i++] = "q\n";
  input[i] = NULL;

  for (int i = 0; input[i]; ++i)
    {
      write (master, input[i], strlen (input[i]));
      sleep (1);
    }
  get_output (master);
  wait (NULL);
}

void
get_output (int fd)
{
  char buf[4096];

  while (1)
    {
      int nread = read (fd, buf, sizeof (buf));
      if (nread > 0)
	write (STDOUT_FILENO, buf, nread);
      else
	{
	  printf ("No more output.  nread %d\n", nread);
	  break;
	}
    }
}




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Re: gdb 7.3.50-2 crash

[Christopher Faylor]

On Thu, Oct 27, 2011 at 08:11:39AM -0400, Ken Brown wrote:
>On 10/16/2011 7:01 AM, Ken Brown wrote:
>> gdb 7.3.50-2 crashes with a segfault if a file is loaded and the
>> following two command lines are sent:
>>
>> server interpreter mi "-file-list-exec-source-files"
>> server list
>
>I don't know if it helps, but I've modified the STC from 
>http://cygwin.com/ml/cygwin/2011-10/msg00472.html to apply to the 
>present problem.  I had to uncomment the sleep (1) to get it to run 
>properly on my Linux system.  I also made the STC run "gdb --annotate=3" 
>even though the crash occurs with just "gdb", because that's how gdb is 
>run by emacs in the situation that led to this bug report.
>
>The STC assumes that you have hello.exe in the current directory.

I haven't tried your new STC but I have confirmed that the crash
goes away with a newer version of gdb.  I'll roll out a new update
over the weekend.

cgf

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