[Bug dynamic-link/16133] New: Access to __thread variable may call malloc

[Bug dynamic-link/16133] New: Access to __thread variable may call malloc

[ppluzhnikov at google dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16133

            Bug ID: 16133
           Summary: Access to __thread variable may call malloc
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: unassigned at sourceware dot org
          Reporter: ppluzhnikov at google dot com

Discussion thread:
https://sourceware.org/ml/libc-alpha/2012-06/msg00335.html

ppluzhnikov>

When writing CPU or heap profilers, one frequently desires to have fast
and async-signal-safe access to thread-local variables.

The __thread variables generally fit the bill (at least on Linux/x86),
when the variable is in the main executable, or in a directly-linked DSO.

But when the DSO is dlopen()ed (and does not use initial-exec TLS model),
the first access to TLS variable from a given thread triggers a call to
malloc (with the following stack):

#0  0x00007f10ea319c97 in malloc () from /lib64/libc.so.6
#1  0x00007f10eac75b6c in tls_get_addr_tail () from /lib64/ld-linux-x86-64.so.2
#2  0x00007f10eac76760 in __tls_get_addr () from /lib64/ld-linux-x86-64.so.2
#3  ... profiler accessing __thread variable ...
#4 <signal handler>

iant>
We are currently in an unpleasant situation where it is very easy and
natural to use TLS variables--you just refer to them by name--and using
them in a signal handler almost always works just fine.  Except that in
some highly specific but not completely implausible circumstances it
crashes incomprehensibly.  This is not a good thing, it's a lurking time
bomb.



Proposed patch:
http://www.sourceware.org/ml/libc-alpha/2013-10/msg00128.html

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[carlos at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16133

Carlos O'Donell <carlos at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |carlos at redhat dot com
   Target Milestone|---                         |2.19

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[ppluzhnikov at google dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16133

Paul Pluzhnikov <ppluzhnikov at google dot com> changed:

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

--- Comment #1 from Paul Pluzhnikov <ppluzhnikov at google dot com> ---
After a long slog, Andrew's patch has been split into 4 and committed:

https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=7f507ee17aee720fa423fa38502bc3caa0dd03d7
https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=1f33d36a8a9e78c81bed59b47f260723f56bb7e6
https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=35e8f7ab94c910659de9d507aa0f3e1f8973d914
https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=69a17d9d245dc3551792e95e1823cc2d877592f3

Note: GNU2 TLS variant is still broken (calls malloc).

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=16133

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".

The branch, master has been updated
       via  a494421f5268df333c589d71104a39bb6a9cff19 (commit)
      from  2112e176757483dd25a7cf38ead63a237bf5e52e (commit)

Those revisions listed above that are new to this repository have
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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a494421f5268df333c589d71104a39bb6a9cff19

commit a494421f5268df333c589d71104a39bb6a9cff19
Author: Paul Pluzhnikov <ppluzhnikov@google.com>
Date:   Sat Jan 11 16:59:43 2014 -0800

    BZ 16133 has been fixed (async signal safe TLS).

-----------------------------------------------------------------------

Summary of changes:
 NEWS |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=16133

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
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The branch, allan/revert-TLS-changes has been created
        at  063f2598738c340558462923d2b17a665713ed2e (commit)

- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=063f2598738c340558462923d2b17a665713ed2e

commit 063f2598738c340558462923d2b17a665713ed2e
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 12:51:40 2014 +1000

    Revert "BZ 16133 has been fixed (async signal safe TLS)."

    This reverts commit a494421f5268df333c589d71104a39bb6a9cff19.

    Conflicts:
        NEWS

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c364820b18326c354ce371daff340b97da3d03db

commit c364820b18326c354ce371daff340b97da3d03db
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 12:20:11 2014 +1000

    Revert "Patch [1/4] async-signal safe TLS."

    This reverts commit 69a17d9d245dc3551792e95e1823cc2d877592f3.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c1543ec02e4dbbb39a7c452f72aa82a933f5232a

commit c1543ec02e4dbbb39a7c452f72aa82a933f5232a
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 12:19:56 2014 +1000

    Revert "Patch 3/4 of the effort to make TLS access async-signal-safe."

    This reverts commit 35e8f7ab94c910659de9d507aa0f3e1f8973d914.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=40cd533ceca15faddd466a7fdd1831d8a1bfbce6

commit 40cd533ceca15faddd466a7fdd1831d8a1bfbce6
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 12:19:19 2014 +1000

    Revert "Patch 2/4 of the effort to make TLS access async-signal-safe."

    This reverts commit 1f33d36a8a9e78c81bed59b47f260723f56bb7e6.

    Conflicts:
        elf/dl-misc.c

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9ca53ad185c8e50d0488ef0a419930e48b14f182

commit 9ca53ad185c8e50d0488ef0a419930e48b14f182
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 12:17:23 2014 +1000

    Revert "Async-signal safe TLS."

    This reverts commit 7f507ee17aee720fa423fa38502bc3caa0dd03d7.

    Conflicts:
        ChangeLog
        nptl/tst-tls7.c
        nptl/tst-tls7mod.c

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=16133

--- Comment #4 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
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The branch, allan/revert-TLS-changes has been deleted
       was  063f2598738c340558462923d2b17a665713ed2e

- Log -----------------------------------------------------------------
063f2598738c340558462923d2b17a665713ed2e Revert "BZ 16133 has been fixed (async
signal safe TLS)."
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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=16133

--- Comment #5 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
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The branch, allan/revert-TLS-changes has been created
        at  b3ece0e0a4912bfedd6da72f2ae1cf5d1b10731b (commit)

- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b3ece0e0a4912bfedd6da72f2ae1cf5d1b10731b

commit b3ece0e0a4912bfedd6da72f2ae1cf5d1b10731b
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:22:19 2014 +1000

    Revert "BZ 16133 has been fixed (async signal safe TLS)."

    This reverts commit a494421f5268df333c589d71104a39bb6a9cff19.

    Conflicts:
        NEWS

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=59cf6f94f13991336bd958a4491ee9d57109a7bd

commit 59cf6f94f13991336bd958a4491ee9d57109a7bd
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:21:09 2014 +1000

    Revert "Patch [1/4] async-signal safe TLS."

    This reverts commit 69a17d9d245dc3551792e95e1823cc2d877592f3.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=097c7e230df0e16bf950456676a48281e9f3a905

commit 097c7e230df0e16bf950456676a48281e9f3a905
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:21:00 2014 +1000

    Revert "Patch 3/4 of the effort to make TLS access async-signal-safe."

    This reverts commit 35e8f7ab94c910659de9d507aa0f3e1f8973d914.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ddd7cff1fc7ca773ee02981f5c2f80116a32b325

commit ddd7cff1fc7ca773ee02981f5c2f80116a32b325
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:19:51 2014 +1000

    Revert "Patch 2/4 of the effort to make TLS access async-signal-safe."

    This reverts commit 1f33d36a8a9e78c81bed59b47f260723f56bb7e6.

    Conflicts:
        elf/dl-misc.c

    Also reverts the follow commits that were bug fixes to new code introduced
    in the above commit:
    063b2acbce83549df82ab30f5af573f1b9c4bd19
    b627fdd58554bc36bd344dc40a8787c4b7a9cc46
    e81c64bba13d2d8b2a4e53254a82cc80f27c8497

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=57f6ca1e5d4d50961e904a986b86174614316653

commit 57f6ca1e5d4d50961e904a986b86174614316653
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:14:59 2014 +1000

    Revert "Async-signal safe TLS."

    This reverts commit 7f507ee17aee720fa423fa38502bc3caa0dd03d7.

    Conflicts:
        ChangeLog
        nptl/tst-tls7.c
        nptl/tst-tls7mod.c

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[ppluzhnikov at google dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16133

Paul Pluzhnikov <ppluzhnikov at google dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unspecified                 |2.19
   Target Milestone|2.19                        |2.20

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[ppluzhnikov at google dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16133

Paul Pluzhnikov <ppluzhnikov at google dot com> changed:

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

--- Comment #6 from Paul Pluzhnikov <ppluzhnikov at google dot com> ---
Fixes reverted. Re-opening.

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=16133

--- Comment #8 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
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The branch, master has been updated
       via  f482dbbec775bf72eb6510b6091fca141893c466 (commit)
       via  bf06bcee84d4c19a99925c0f58026a8cbd87a688 (commit)
       via  8b6785f0836011cace9a77f3c24e51a7379238a0 (commit)
       via  dd654bf9ba1848bf9ed250f8ebaa5097c383dcf8 (commit)
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Those revisions listed above that are new to this repository have
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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f482dbbec775bf72eb6510b6091fca141893c466

commit f482dbbec775bf72eb6510b6091fca141893c466
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:22:19 2014 +1000

    Revert "BZ 16133 has been fixed (async signal safe TLS)."

    This reverts commit a494421f5268df333c589d71104a39bb6a9cff19.

    Conflicts:
        NEWS

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=bf06bcee84d4c19a99925c0f58026a8cbd87a688

commit bf06bcee84d4c19a99925c0f58026a8cbd87a688
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:21:09 2014 +1000

    Revert "Patch [1/4] async-signal safe TLS."

    This reverts commit 69a17d9d245dc3551792e95e1823cc2d877592f3.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8b6785f0836011cace9a77f3c24e51a7379238a0

commit 8b6785f0836011cace9a77f3c24e51a7379238a0
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:21:00 2014 +1000

    Revert "Patch 3/4 of the effort to make TLS access async-signal-safe."

    This reverts commit 35e8f7ab94c910659de9d507aa0f3e1f8973d914.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=dd654bf9ba1848bf9ed250f8ebaa5097c383dcf8

commit dd654bf9ba1848bf9ed250f8ebaa5097c383dcf8
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:19:51 2014 +1000

    Revert "Patch 2/4 of the effort to make TLS access async-signal-safe."

    This reverts commit 1f33d36a8a9e78c81bed59b47f260723f56bb7e6.

    Conflicts:
        elf/dl-misc.c

    Also reverts the follow commits that were bug fixes to new code introduced
    in the above commit:
    063b2acbce83549df82ab30f5af573f1b9c4bd19
    b627fdd58554bc36bd344dc40a8787c4b7a9cc46
    e81c64bba13d2d8b2a4e53254a82cc80f27c8497

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=73d61e4f6c65da714c0f8a3a233725322553ceba

commit 73d61e4f6c65da714c0f8a3a233725322553ceba
Author: Allan McRae <allan@archlinux.org>
Date:   Wed Feb 5 21:14:59 2014 +1000

    Revert "Async-signal safe TLS."

    This reverts commit 7f507ee17aee720fa423fa38502bc3caa0dd03d7.

    Conflicts:
        ChangeLog
        nptl/tst-tls7.c
        nptl/tst-tls7mod.c

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                           |   46 -----------
 NEWS                                |   12 ++--
 elf/Versions                        |    1 -
 elf/dl-misc.c                       |  142 ----------------------------------
 elf/dl-open.c                       |    5 +-
 elf/dl-reloc.c                      |   48 +----------
 elf/dl-tls.c                        |  144 ++++++++++++-----------------------
 nptl/ChangeLog                      |    9 +--
 nptl/Makefile                       |   12 +---
 nptl/allocatestack.c                |   19 ++---
 nptl/tst-tls7.c                     |  143 ----------------------------------
 nptl/tst-tls7mod.c                  |   40 ----------
 sysdeps/generic/ldsodefs.h          |   16 ----
 sysdeps/mach/hurd/dl-sysdep.h       |    7 --
 sysdeps/unix/sysv/linux/dl-sysdep.c |   46 -----------
 sysdeps/unix/sysv/linux/dl-sysdep.h |    4 -
 16 files changed, 72 insertions(+), 622 deletions(-)
 delete mode 100644 nptl/tst-tls7.c
 delete mode 100644 nptl/tst-tls7mod.c

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[Bug dynamic-link/16133] Access to __thread variable may call malloc

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http://sourceware.org/bugzilla/show_bug.cgi?id=16133

--- Comment #7 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
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The branch, allan/revert-TLS-changes has been deleted
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- Log -----------------------------------------------------------------
b3ece0e0a4912bfedd6da72f2ae1cf5d1b10731b Revert "BZ 16133 has been fixed (async
signal safe TLS)."
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[Bug dynamic-link/16133] Access to __thread variable may call malloc

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16133

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com

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