[Bug libc/11655] New: qsort() not thread safe, results to division by zero

[tmo at iki dot fi]

Function qsort_r() is not thread-safe. This results to division by zero if two
threads call it at the same time, and both sort more than 1024 bytes of data. 

Function contains code fragment 
--
[A] if (phys_pages == 0) {
  phys_pages = sysconf()
  ...
  pagesize = sysconf()
}

[B] if (size / pagesize > phys_pages) 
--

The first thread detects phys_pages being zero on [A] and may not yet have
assigned pagesize, when the second thread enters the code, sees phys_pages being
nonzero at [A], and performs division by zero pagesize at [B].

BR
--
Tero Mononen <tmo@iki.fi>

-- 
           Summary: qsort() not thread safe, results to division by zero
           Product: glibc
           Version: 2.12
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: tmo at iki dot fi
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=11655

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