[Bug libc/1973] New: getenv returns pointer to unallocated space.

[Bug libc/1973] New: getenv returns pointer to unallocated space.

[marvin dot nospam at gmail dot com]

The following code results in a segmentation faul on an AMD64.
---------------------------------
char	*home_dir;

home_dir = (char *)getenv("HOME");
if (home_dir != NULL)
{
	printf ("$HOME = %s\n", home_dir);
}
---------------------------------

On my system it works fine but on the system of an user of my program
(keytouch), running gentoo, it crashes.

-- 
           Summary: getenv returns pointer to unallocated space.
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P3
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: marvin dot nospam at gmail dot com
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=1973

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[Bug libc/1973] getenv returns pointer to unallocated space.

[marvin dot nospam at gmail dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unspecified                 |2.3.5


http://sourceware.org/bugzilla/show_bug.cgi?id=1973

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[Bug libc/1973] getenv returns pointer to unallocated space.

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2005-12-03 16:18 -------
It of course works for everybody since otherwise all  hell would break lose.  If
there is some problem somewhere it must be local and you have to investigate
this yourself.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WORKSFORME


http://sourceware.org/bugzilla/show_bug.cgi?id=1973

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[Bug libc/1973] getenv returns pointer to unallocated space.

[marvin dot nospam at gmail dot com]

------- Additional Comments From marvin dot nospam at gmail dot com  2006-01-21 17:45 -------
I received more e-mails from people reporting this segmentation fault in my
program. I know what you are thinking ("it is a bug in your program"), but just
look at the code:
---------------------------------
void
read_plugins (KTPluginList *plugin_list)
/*
Input:
	-
Output:
	plugin_list	- The plugins are added to this list.
Returns:
	-
Description:
	This function reads the plugins from the plugin directories and adds them to
	plugin_list.
*/
{
	char	*home_dir,
		*local_plugin_dir;
	int	local_plugin_dir_len;
	
	read_plugin_dir (PLUGIN_DIR, plugin_list);
	home_dir = (char *)getenv("HOME");
	if (home_dir != NULL)
	{
		local_plugin_dir_len = strlen(home_dir)+strlen("/"LOCAL_PLUGIN_DIR);
		local_plugin_dir = keytouch_malloc(local_plugin_dir_len+1);
		strcpy (local_plugin_dir, home_dir);
		strcat (local_plugin_dir, "/"LOCAL_PLUGIN_DIR);
		read_plugin_dir (local_plugin_dir, plugin_list);
		free (local_plugin_dir);
	}
}
---------------------------------

I only received reports from people using an AMD64.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|WORKSFORME                  |


http://sourceware.org/bugzilla/show_bug.cgi?id=1973

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[Bug libc/1973] getenv returns pointer to unallocated space.

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2006-01-21 18:04 -------
You haven't shown one shred of evidence that this is a problem in the
implementation.  What is more likely:

- the implementation is buggy and millions of people are just lucky

- your one program see this problem and nobody else


There is no x86-64 specific code in the environment variable handling.  Look at
your code, run it with valgrind.  Determine whether you use putenv somewhere. 
If yes, learn about the difference between setenv and putenv.

Until you have a self-contained program which shows the problem do not reopen
the bug.  We are not going to help you debug your appication.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |WORKSFORME


http://sourceware.org/bugzilla/show_bug.cgi?id=1973

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[Bug libc/1973] getenv returns pointer to unallocated space.

[lepinat at free dot fr]

------- Additional Comments From lepinat at free dot fr  2006-04-03 18:51 -------
I found where the problem come from, but I can't understand why it's append,
 and I would like to know.
On the samples sended  by marvin.nospam@gmail.com

if it compiled on the 32bits mode (-m32) no problem
if it compiled on the 64bits mode (-m64) SegFault

on the samples if we add the line #include <stdlib.h> on the 64bits mode, 
the problem disappear!

---->8---->8---->8-----
# Makefile
CC:=gcc
#CFLAGS:=-enable-checking -g -O0 -v -Q -da
CFLAGS:= -g

BINARY:= test_getenv64 test_getenv64_segfault test_getenv32

all: $(BINARY)

test_getenv64_segfault: test_getenv.c
	$(CC) $(CFLAGS)  $^ -o $@

test_getenv64: test_getenv.c
	$(CC) $(CFLAGS) -DNO_FAULT $^ -o $@

test_getenv32: test_getenv.c
	$(CC) $(CFLAGS) $^ -o $@

clean:
	rm -f *.o $(BINARY) 

---->8---->8---->8-----
/* test_getenv.c */
#include <stdio.h>

#ifdef NO_FAULT
#include <stdlib.h>
#endif

main()
{
    char *home =  getenv("HOME");
    if (!home)	{
        printf("ptr=NULL\n");
    }
    else {
        printf ("path=%s\n", home);
    }
}




-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
              Alias|                            |getenv_problem
             Status|RESOLVED                    |REOPENED
 GCC target triplet|                            |x86_64
         Resolution|WORKSFORME                  |


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[Bug libc/1973] getenv returns pointer to unallocated space.

[jakub at redhat dot com]

------- Additional Comments From jakub at redhat dot com  2006-04-03 20:22 -------
You couldn't be bothered to at least compile your testcase with -Wall?
gcc would warn you about implicit declaration of getenv function.
Implicitly declared functions have int return type, but getenv realllly returns
a pointer, so in your testcase when you mistakenly don't include stdlib.h,
the resulting pointer gets upper 32 bits sign-extended from bit 31 of the
pointer.
Please don't reopen any longer and spend some time reading ISO C99.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |INVALID


http://sourceware.org/bugzilla/show_bug.cgi?id=1973

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