[Bug dynamic-link/15686] New: Shared-object static constructors called with a lock held

[Bug dynamic-link/15686] New: Shared-object static constructors called with a lock held

[macro@linux-mips.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15686

            Bug ID: 15686
           Summary: Shared-object static constructors called with a lock
                    held
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: unassigned at sourceware dot org
          Reporter: macro@linux-mips.org
                CC: macro@linux-mips.org
            Target: *-*-*

Shared-object static constructors are user code that the C library has no
control of.  They are called with the GL(dl_load_lock) lock held and are
therefore prone to a deadlock if they call back into the wrong part of
ld.so.  The exact call sequence is:

_dl_open -> dl_open_worker -> _dl_init -> call_init -> user code

and in the sequence above _dl_open takes the GL(dl_load_lock) lock before
calling dl_open_worker.  This affects all targets.

See also:

http://sourceware.org/ml/libc-alpha/2013-06/msg00802.html
http://sourceware.org/ml/libc-alpha/2013-06/msg00828.html

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[Bug dynamic-link/15686] Shared-object static constructors called with a lock held

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15686

Florian Weimer <fweimer at redhat dot com> changed:

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

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[Bug dynamic-link/15686] Shared-object static constructors called with a lock held

[nsz at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=15686

Szabolcs Nagy <nsz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nsz at gcc dot gnu.org

--- Comment #3 from Szabolcs Nagy <nsz at gcc dot gnu.org> ---
note: deadlock can happen without thread creation from ctors:

thread 1: dlopen -> dl_load_lock -> ctor -> user_lock

thread 2: user_lock -> dlsym/dlopen/dlclose -> dl_load_lock


if calling dlsym/dlopen/dlclose/.. from a ctor is allowed
then i'd expect this to work too, but now it deadlocks.

the fix for bug 19329 added the same lock to pthread_create
so now this problem affects more code.

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[Bug dynamic-link/15686] Shared-object static constructors called with a lock held

[nsz at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=15686

--- Comment #4 from Szabolcs Nagy <nsz at gcc dot gnu.org> ---
i opened bug 28357 for the deadlock with pthread_create.

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