[Bug libc/11292] New: __init_cpu_features race

[Bug libc/11292] New: __init_cpu_features race

[jan dot kratochvil at redhat dot com]

ifunc resolver can be called from multiple threads at once.

./sysdeps/x86_64/multiarch/init-arch.c
struct cpu_features __cpu_features attribute_hidden;
__init_cpu_features:
          __cpu_features.family += extended_family;

This is a race, __cpu_features is global and it has no locks being held.

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           Summary: __init_cpu_features race
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: minor
          Priority: P3
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: jan dot kratochvil at redhat dot com
                CC: glibc-bugs at sources dot redhat dot com
  GCC host triplet: x86_64-unknown-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=11292

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[Bug libc/11292] __init_cpu_features race

[jan dot kratochvil at redhat dot com]

------- Additional Comments From jan dot kratochvil at redhat dot com  2010-02-17 17:30 -------
Pointed out by Pedro Alves:
http://sourceware.org/ml/gdb-patches/2010-02/msg00420.html


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http://sourceware.org/bugzilla/show_bug.cgi?id=11292

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[Bug libc/11292] __init_cpu_features race

[hjl dot tools at gmail dot com]

------- Additional Comments From hjl dot tools at gmail dot com  2010-02-17 17:43 -------
We can rearrange __init_cpu_features such that all bits in
__cpu_features are write-only.

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           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl dot tools at gmail dot
                   |                            |com


http://sourceware.org/bugzilla/show_bug.cgi?id=11292

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[Bug libc/11292] __init_cpu_features race

[hjl dot tools at gmail dot com]

------- Additional Comments From hjl dot tools at gmail dot com  2010-02-17 17:54 -------
Created an attachment (id=4607)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4607&action=view)
A patch


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[Bug libc/11292] __init_cpu_features race

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2010-04-04 07:26 -------
HJ's patch is OK but incomplete.  There is another race.  The kind field must
only be changed once the other fields are committed to memory.  I made that
change as well.

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


http://sourceware.org/bugzilla/show_bug.cgi?id=11292

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[Bug libc/11292] __init_cpu_features race

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=11292

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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