[Bug libc/6712] New: Race condition in calling setlocale()

[Bug libc/6712] New: Race condition in calling setlocale()

[sharyathi at in dot ibm dot com]

Description

During PHP engine development it was observed that a thread calling
strcmp() would crash if another thread was also calling setlocale().
The problem is difficult to reproduce, but the following is a
line-by-line analysis of where the race condition exists.
-----------------------------------------------------------------------
char *
setlocale (int category, const char *locale)
{
  char *locale_path;
  .......
 /* Does user want name of current locale?  */
  if (locale == NULL)
    return (char *) _nl_global_locale.__names[category];

  if (strcmp (locale, _nl_global_locale.__names[category]) == 0)
<== SIGSEGVs while accessing _nl_global_locale

  ..........


if (category == LC_ALL)
    {
  ..........
/* Protect global data.  */
      __libc_rwlock_wrlock (__libc_setlocale_lock);
  ..........
setname (LC_ALL, composite)
<== Frees the global variable _nl_global_locale.__names[category]

..........
 /* Critical section left.  */
      __libc_rwlock_unlock (__libc_setlocale_lock);
} //category == LC_ALL

  ..........


} //setlocale end of function
-----------------------------------------------------------------------
Though setlocale() is not on the POSIX.1 list of async-signal safe
functions as in section 2.4.3
http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html#tag_02_04

It still needs to be thread safe according to section 2.9.1 in
http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_09.html

-- 
           Summary: Race condition in calling setlocale()
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: sharyathi at in dot ibm dot com
                CC: bmark at us dot ibm dot com,glibc-bugs at sources dot
                    redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6712

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug libc/6712] Race condition in calling setlocale()

[sharyathi at in dot ibm dot com]

------- Additional Comments From sharyathi at in dot ibm dot com  2008-07-01 11:11 -------
Created an attachment (id=2810)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2810&action=view)
Change log for the patch

This is the change log for the proposed patch

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6712

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug libc/6712] Race condition in calling setlocale()

[sharyathi at in dot ibm dot com]

------- Additional Comments From sharyathi at in dot ibm dot com  2008-07-01 11:13 -------
Created an attachment (id=2811)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2811&action=view)
Patch to fix the setlocale race issue

This is the proposed fix to the problem
Testing of the patch
    There was no regression observed while testing. Testing was done on
x86_64-linux-gnu box where the application was built as 32 bit. 

Thanks
Sharyathi

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6712

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug libc/6712] Race condition in calling setlocale()

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2008-07-20 17:29 -------
I checked in a different patch.

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


http://sourceware.org/bugzilla/show_bug.cgi?id=6712

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug libc/6712] Race condition in calling setlocale()

[sharyathi at in dot ibm dot com]

------- Additional Comments From sharyathi at in dot ibm dot com  2008-07-23 08:38 -------
Ulrich
  Can you point to the patch added to glibc
Thanks
Sharyathi

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6712

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.