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Stefan Metzmacher ee02e40e86 ctdb-locking: Avoid memory corruption in ctdb_lock_context_destructor
If the lock request is freed from within the callback, then setting
lock_ctx->request to NULL in ctdb_lock_context_destructor will end up
corrupting memory.  In this case, lock_ctx->request could be reallocated
and pointing to something else.  This may cause unexpected abort trying
to dereference a NULL pointer.

So, set lock_ctx->request to NULL before processing callbacks.

This avoids the following valgrind problem.

==3636== Invalid write of size 8
==3636==    at 0x151F3D: ctdb_lock_context_destructor (ctdb_lock.c:276)
==3636==    by 0x58B3618: _talloc_free_internal (talloc.c:993)
==3636==    by 0x58AD692: _talloc_free_children_internal (talloc.c:1472)
==3636==    by 0x58AD692: _talloc_free_internal (talloc.c:1019)
==3636==    by 0x58AD692: _talloc_free (talloc.c:1594)
==3636==    by 0x15292E: ctdb_lock_handler (ctdb_lock.c:471)
==3636==    by 0x56A535A: epoll_event_loop (tevent_epoll.c:728)
==3636==    by 0x56A535A: epoll_event_loop_once (tevent_epoll.c:926)
==3636==    by 0x56A3826: std_event_loop_once (tevent_standard.c:114)
==3636==    by 0x569FFFC: _tevent_loop_once (tevent.c:533)
==3636==    by 0x56A019A: tevent_common_loop_wait (tevent.c:637)
==3636==    by 0x56A37C6: std_event_loop_wait (tevent_standard.c:140)
==3636==    by 0x11E03A: ctdb_start_daemon (ctdb_daemon.c:1320)
==3636==    by 0x118557: main (ctdbd.c:321)
==3636==  Address 0x9c5b660 is 96 bytes inside a block of size 120 free'd
==3636==    at 0x4C29D17: free (in
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==3636==    by 0x58B32D3: _talloc_free_internal (talloc.c:1063)
==3636==    by 0x58B3232: _talloc_free_children_internal (talloc.c:1472)
==3636==    by 0x58B3232: _talloc_free_internal (talloc.c:1019)
==3636==    by 0x58B3232: _talloc_free_children_internal (talloc.c:1472)
==3636==    by 0x58B3232: _talloc_free_internal (talloc.c:1019)
==3636==    by 0x58AD692: _talloc_free_children_internal (talloc.c:1472)
==3636==    by 0x58AD692: _talloc_free_internal (talloc.c:1019)
==3636==    by 0x58AD692: _talloc_free (talloc.c:1594)
==3636==    by 0x11EC30: daemon_incoming_packet (ctdb_daemon.c:844)
==3636==    by 0x136F4A: lock_fetch_callback (ctdb_ltdb_server.c:268)
==3636==    by 0x152489: process_callbacks (ctdb_lock.c:353)
==3636==    by 0x152489: ctdb_lock_handler (ctdb_lock.c:468)
==3636==    by 0x56A535A: epoll_event_loop (tevent_epoll.c:728)
==3636==    by 0x56A535A: epoll_event_loop_once (tevent_epoll.c:926)
==3636==    by 0x56A3826: std_event_loop_once (tevent_standard.c:114)
==3636==    by 0x569FFFC: _tevent_loop_once (tevent.c:533)
==3636==    by 0x56A019A: tevent_common_loop_wait (tevent.c:637)
==3636==    by 0x56A37C6: std_event_loop_wait (tevent_standard.c:140)
==3636==    by 0x11E03A: ctdb_start_daemon (ctdb_daemon.c:1320)
==3636==    by 0x118557: main (ctdbd.c:321)

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11293

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
2015-06-12 12:40:53 +02:00
..
2015-04-21 19:37:16 +02:00
2013-10-30 15:37:54 +11:00
2007-06-07 22:16:48 +10:00
2009-02-07 08:10:34 +11:00
2013-11-27 18:46:17 +01:00

This is the release version of CTDB, a clustered implementation of TDB
database used by Samba and other projects to store temporary data.

This software is freely distributable under the GNU public license,
a copy of which you should have received with this software (in a file
called COPYING).

For documentation on CTDB, please visit CTDB website http://ctdb.samba.org.