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From: "ian at airs dot com" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
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This is the linuxthreads version of bugzilla PR 3317, which I reported for NPTL.

If I override the libc free() function, and change that function to clobber some
bytes of the data, and then call pthread_getspecific from that function,
pthread_getspecific can return bad data.  This is because
__pthread_destroy_specifics frees memory before clearing the pointer to it. 
This happens around line 200:

    if (THREAD_GETMEM_NC(self, p_specific[i]) != NULL) {
      free(THREAD_GETMEM_NC(self, p_specific[i]));
      THREAD_SETMEM_NC(self, p_specific[i], NULL);
    }

This should be rewritten to call THREAD_GETMEM_NC, then THREAD_SETMEM_NC, then free.

I will attach a test case which shows the problem on i686-pc-linux-gnu using
Fedora Core 4 with glibc-2.3.6-3 when setting the environment variable
LD_ASSUME_KERNEL to 2.4.19.

-- 
           Summary: Overriding free which clobbers data and calls
                    pthread_getspecific can get bad value (linuxthreads)
           Product: glibc
           Version: 2.3.6
            Status: NEW
          Severity: normal
          Priority: P2
         Component: linuxthreads
        AssignedTo: drow at false dot org
        ReportedBy: ian at airs dot com
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=3318

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