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dd516b9baf
We protect setting tctx->event_ctx=NULL with tctx->event_ctx_mutex.
But in _tevent_threaded_schedule_immediate we have the classic
TOCTOU race: After we checked "ev==NULL", looking at
tevent_common_context_destructor the event context can go after
_tevent_threaded_schedule_immediate checked. We need to serialize
things a bit by keeping tctx->event_ctx_mutex locked while we
reference "ev", in particular in the
DLIST_ADD_END(ev->scheduled_immediates,im);
I think the locking hierarchy is still maintained, tevent_atfork_prepare()
first locks all the tctx locks, and then the scheduled_mutex. Also,
I don't think this will impact parallelism too badly: event_ctx_mutex
is only used to protect setting tctx->ev.
Found by staring at code while fixing the FreeBSD memleak due to
not destroying scheduled_mutex.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Jun 9 00:45:26 CEST 2017 on sn-devel-144
(cherry picked from commit
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|---|---|---|
| .. | ||
| addns | ||
| afs | ||
| async_req | ||
| compression | ||
| crypto | ||
| dbwrap | ||
| krb5_wrap | ||
| ldb | ||
| ldb-samba | ||
| nss_wrapper | ||
| param | ||
| replace | ||
| resolv_wrapper | ||
| smbconf | ||
| socket | ||
| socket_wrapper | ||
| talloc | ||
| tdb | ||
| tdb_wrap | ||
| tdr | ||
| tevent | ||
| texpect | ||
| torture | ||
| tsocket | ||
| uid_wrapper | ||
| util | ||
| README | ||
| wscript_build | ||
compression - Various compression algorithms (MSZIP, lzxpress)
dnspython - Python module for working with DNS.
nss_wrapper - Wrapper for the user and group NSS API allowing the use
of other data sources.
popt - Command-line option parsing library
replace - Provides replacements for standard (POSIX, C99) functions
not provided by the host platform.
socket_wrapper - Wrapper library allowing TCP/IP traffic to be redirected
over Unix domain sockets.
subunit - Utilities and bindings for working with the Subunit test result
reporting protocol.
talloc - Hierarchical pool based memory allocator
tdb - Simple but fast key/value database library, supporting multiple writers
torture - Simple unit testing helper library