diff options
| -rw-r--r-- | ChangeLog | 14 | ||||
| -rw-r--r-- | elf/Makefile | 14 | ||||
| -rw-r--r-- | elf/dl-close.c | 30 | ||||
| -rw-r--r-- | elf/tst-nodelete-dlclose-dso.c | 90 | ||||
| -rw-r--r-- | elf/tst-nodelete-dlclose-plugin.c | 40 | ||||
| -rw-r--r-- | elf/tst-nodelete-dlclose.c | 35 |
6 files changed, 215 insertions, 8 deletions
@@ -1,3 +1,17 @@ +2016-12-24 Carlos O'Donell <carlos@redhat.com> + + [BZ #11941] + * elf/dl-close.c (_dl_close): Take dl_load_lock to examine map. + Remove assert (map->l_init_called); if DF_1_NODELETE is set. + * elf/Makefile [ifeq (yes,$(build-shared))] (tests): Add + tst-nodelete-dlclose. + (modules-names): Add tst-nodelete-dlclose-dso and + tst-nodelete-dlclose-plugin. + ($(objpfx)tst-nodelete-dlclose-dso.so): Define. + ($(objpfx)tst-nodelete-dlclose-plugin.so): Define. + ($(objpfx)tst-nodelete-dlclose): Define. + ($(objpfx)tst-nodelete-dlclose.out): Define. + 2016-12-23 Florian Weimer <fweimer@redhat.com> * scripts/test_printers_common.py: Log GDB output in case of diff --git a/elf/Makefile b/elf/Makefile index 330397e5d8..cd26e16558 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -152,7 +152,7 @@ tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \ tst-initorder tst-initorder2 tst-relsort1 tst-null-argv \ tst-ptrguard1 tst-tlsalign tst-tlsalign-extern tst-nodelete-opened \ tst-nodelete2 tst-audit11 tst-audit12 tst-dlsym-error tst-noload \ - tst-latepthread tst-tls-manydynamic + tst-latepthread tst-tls-manydynamic tst-nodelete-dlclose # reldep9 ifeq ($(build-hardcoded-path-in-tests),yes) tests += tst-dlopen-aout @@ -231,7 +231,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \ tst-tlsalign-lib tst-nodelete-opened-lib tst-nodelete2mod \ tst-audit11mod1 tst-audit11mod2 tst-auditmod11 \ tst-audit12mod1 tst-audit12mod2 tst-audit12mod3 tst-auditmod12 \ - tst-latepthreadmod $(tst-tls-many-dynamic-modules) + tst-latepthreadmod $(tst-tls-many-dynamic-modules) \ + tst-nodelete-dlclose-dso tst-nodelete-dlclose-plugin ifeq (yes,$(have-mtls-dialect-gnu2)) tests += tst-gnu2-tls1 modules-names += tst-gnu2-tls1mod @@ -1345,3 +1346,12 @@ ifeq (no,$(nss-crypt)) $(objpfx)tst-linkall-static: \ $(common-objpfx)crypt/libcrypt.a endif + +# The application depends on the DSO, and the DSO loads the plugin. +# The plugin also depends on the DSO. This creates the circular +# dependency via dlopen that we're testing to make sure works. +$(objpfx)tst-nodelete-dlclose-dso.so: $(libdl) +$(objpfx)tst-nodelete-dlclose-plugin.so: $(objpfx)tst-nodelete-dlclose-dso.so +$(objpfx)tst-nodelete-dlclose: $(objpfx)tst-nodelete-dlclose-dso.so +$(objpfx)tst-nodelete-dlclose.out: $(objpfx)tst-nodelete-dlclose-dso.so \ + $(objpfx)tst-nodelete-dlclose-plugin.so diff --git a/elf/dl-close.c b/elf/dl-close.c index 648970332e..9f93ab7628 100644 --- a/elf/dl-close.c +++ b/elf/dl-close.c @@ -805,19 +805,37 @@ _dl_close (void *_map) { struct link_map *map = _map; - /* First see whether we can remove the object at all. */ + /* We must take the lock to examine the contents of map and avoid + concurrent dlopens. */ + __rtld_lock_lock_recursive (GL(dl_load_lock)); + + /* At this point we are guaranteed nobody else is touching the list of + loaded maps, but a concurrent dlclose might have freed our map + before we took the lock. There is no way to detect this (see below) + so we proceed assuming this isn't the case. First see whether we + can remove the object at all. */ if (__glibc_unlikely (map->l_flags_1 & DF_1_NODELETE)) { - assert (map->l_init_called); /* Nope. Do nothing. */ + __rtld_lock_unlock_recursive (GL(dl_load_lock)); return; } + /* At present this is an unreliable check except in the case where the + caller has recursively called dlclose and we are sure the link map + has not been freed. In a non-recursive dlclose the map itself + might have been freed and this access is potentially a data race + with whatever other use this memory might have now, or worse we + might silently corrupt memory if it looks enough like a link map. + POSIX has language in dlclose that appears to guarantee that this + should be a detectable case and given that dlclose should be threadsafe + we need this to be a reliable detection. + This is bug 20990. */ if (__builtin_expect (map->l_direct_opencount, 1) == 0) - _dl_signal_error (0, map->l_name, NULL, N_("shared object not open")); - - /* Acquire the lock. */ - __rtld_lock_lock_recursive (GL(dl_load_lock)); + { + __rtld_lock_unlock_recursive (GL(dl_load_lock)); + _dl_signal_error (0, map->l_name, NULL, N_("shared object not open")); + } _dl_close_worker (map, false); diff --git a/elf/tst-nodelete-dlclose-dso.c b/elf/tst-nodelete-dlclose-dso.c new file mode 100644 index 0000000000..dd930f99cc --- /dev/null +++ b/elf/tst-nodelete-dlclose-dso.c @@ -0,0 +1,90 @@ +/* Bug 11941: Improper assert map->l_init_called in dlclose. + Copyright (C) 2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* This is the primary DSO that is loaded by the appliation. This DSO + then loads a plugin with RTLD_NODELETE. This plugin depends on this + DSO. This dependency chain means that at application shutdown the + plugin will be destructed first. Thus by the time this DSO is + destructed we will be calling dlclose on an object that has already + been destructed. It is allowed to call dlclose in this way and + should not assert. */ +#include <stdio.h> +#include <stdlib.h> +#include <dlfcn.h> + +/* Plugin to load. */ +static void *plugin_lib = NULL; +/* Plugin function. */ +static void (*plugin_func) (void); +#define LIB_PLUGIN "tst-nodelete-dlclose-plugin.so" + +/* This function is never called but the plugin references it. + We do this to avoid any future --as-needed from removing the + plugin's DT_NEEDED on this DSO (required for the test). */ +void +primary_reference (void) +{ + printf ("INFO: Called primary_reference function.\n"); +} + +void +primary (void) +{ + char *error; + + plugin_lib = dlopen (LIB_PLUGIN, RTLD_NOW | RTLD_LOCAL | RTLD_NODELETE); + if (plugin_lib == NULL) + { + printf ("ERROR: Unable to load plugin library.\n"); + exit (EXIT_FAILURE); + } + dlerror (); + + plugin_func = (void (*) (void)) dlsym (plugin_lib, "plugin_func"); + error = dlerror (); + if (error != NULL) + { + printf ("ERROR: Unable to find symbol with error \"%s\".", + error); + exit (EXIT_FAILURE); + } + + return; +} + +__attribute__ ((destructor)) +static void +primary_dtor (void) +{ + int ret; + + printf ("INFO: Calling primary destructor.\n"); + + /* The destructor runs in the test driver also, which + hasn't called primary, in that case do nothing. */ + if (plugin_lib == NULL) + return; + + ret = dlclose (plugin_lib); + if (ret != 0) + { + printf ("ERROR: Calling dlclose failed with \"%s\"\n", + dlerror ()); + exit (EXIT_FAILURE); + } +} diff --git a/elf/tst-nodelete-dlclose-plugin.c b/elf/tst-nodelete-dlclose-plugin.c new file mode 100644 index 0000000000..8b295c1718 --- /dev/null +++ b/elf/tst-nodelete-dlclose-plugin.c @@ -0,0 +1,40 @@ +/* Bug 11941: Improper assert map->l_init_called in dlclose. + Copyright (C) 2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* This DSO simulates a plugin with a dependency on the + primary DSO loaded by the appliation. */ +#include <stdio.h> + +extern void primary_reference (void); + +void +plugin_func (void) +{ + printf ("INFO: Calling plugin function.\n"); + /* Need a reference to the DSO to ensure that a potential --as-needed + doesn't remove the DT_NEEDED entry which we rely upon to ensure + destruction ordering. */ + primary_reference (); +} + +__attribute__ ((destructor)) +static void +plugin_dtor (void) +{ + printf ("INFO: Calling plugin destructor.\n"); +} diff --git a/elf/tst-nodelete-dlclose.c b/elf/tst-nodelete-dlclose.c new file mode 100644 index 0000000000..a12f929aa3 --- /dev/null +++ b/elf/tst-nodelete-dlclose.c @@ -0,0 +1,35 @@ +/* Bug 11941: Improper assert map->l_init_called in dlclose. + Copyright (C) 2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* This simulates an application using the primary DSO which loads the + plugin DSO. */ +#include <stdio.h> +#include <stdlib.h> + +extern void primary (void); + +static int +do_test (void) +{ + printf ("INFO: Starting application.\n"); + primary (); + printf ("INFO: Exiting application.\n"); + return 0; +} + +#include <support/test-driver.c> |