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Always call destructors in reverse constructor order (#2233338)

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Resolves: #2233338
This commit is contained in:
Florian Weimer 2023-09-11 10:54:17 +02:00
parent 653ef302d2
commit 53877e8f4e
7 changed files with 1127 additions and 1 deletions
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commit 7b5bfe77836442b9aeb75cc520f0d1eb7f82be67
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon May 18 15:21:04 2020 +0200
elf: Assert that objects are relocated before their constructors run
If we try to run constructors before relocation, this is always
a dynamic linker bug. An assert is easier to notice than a call
via an invalid function pointer (which may not even produce a valid
call stack).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
diff --git a/elf/dl-init.c b/elf/dl-init.c
index 45405cd0563845b4..99ce531d7b326f5f 100644
--- a/elf/dl-init.c
+++ b/elf/dl-init.c
@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <assert.h>
#include <stddef.h>
#include <ldsodefs.h>
@@ -27,6 +28,11 @@ typedef void (*init_t) (int, char **, char **);
static void
call_init (struct link_map *l, int argc, char **argv, char **env)
{
+ /* If the object has not been relocated, this is a bug. The
+ function pointers are invalid in this case. (Executables do not
+ need relocation, and neither do proxy objects.) */
+ assert (l->l_real->l_relocated || l->l_real->l_type == lt_executable);
+
if (l->l_init_called)
/* This object is all done. */
return;

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commit 6f360366f7f76b158a0f4bf20d42f2854ad56264
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Oct 27 11:36:44 2022 +0200
elf: Introduce to _dl_call_fini
This consolidates the destructor invocations from _dl_fini and
dlclose. Remove the micro-optimization that avoids
calling _dl_call_fini if they are no destructors (as dlclose is quite
expensive anyway). The debug log message is now printed
unconditionally.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Conflicts:
elf/dl-fini.c
(Missing ELF_INITFINI support downstream.)
sysdeps/generic/ldsodefs.h
(Missing dl_init_t declaration downstream.)
diff --git a/elf/Makefile b/elf/Makefile
index 634c3113227d64a6..040d82e243a80c0f 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -50,6 +50,7 @@ routines = \
# profiled libraries.
dl-routines = \
dl-call-libc-early-init \
+ dl-call_fini \
dl-close \
dl-debug \
dl-deps \
diff --git a/elf/dl-call_fini.c b/elf/dl-call_fini.c
new file mode 100644
index 0000000000000000..9e7ba10fa2a4df77
--- /dev/null
+++ b/elf/dl-call_fini.c
@@ -0,0 +1,50 @@
+/* Invoke DT_FINI and DT_FINI_ARRAY callbacks.
+ Copyright (C) 1996-2022 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <ldsodefs.h>
+#include <sysdep.h>
+
+void
+_dl_call_fini (void *closure_map)
+{
+ struct link_map *map = closure_map;
+
+ /* When debugging print a message first. */
+ if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS))
+ _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n", map->l_name, map->l_ns);
+
+ /* Make sure nothing happens if we are called twice. */
+ map->l_init_called = 0;
+
+ ElfW(Dyn) *fini_array = map->l_info[DT_FINI_ARRAY];
+ if (fini_array != NULL)
+ {
+ ElfW(Addr) *array = (ElfW(Addr) *) (map->l_addr
+ + fini_array->d_un.d_ptr);
+ size_t sz = (map->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
+ / sizeof (ElfW(Addr)));
+
+ while (sz-- > 0)
+ ((fini_t) array[sz]) ();
+ }
+
+ /* Next try the old-style destructor. */
+ ElfW(Dyn) *fini = map->l_info[DT_FINI];
+ if (fini != NULL)
+ DL_CALL_DT_FINI (map, ((void *) map->l_addr + fini->d_un.d_ptr));
+}
diff --git a/elf/dl-close.c b/elf/dl-close.c
index 22225efb3226c3e1..26ea51dfbadc5b85 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -35,11 +35,6 @@
#include <dl-unmap-segments.h>
-
-/* Type of the constructor functions. */
-typedef void (*fini_t) (void);
-
-
/* Special l_idx value used to indicate which objects remain loaded. */
#define IDX_STILL_USED -1
@@ -109,31 +104,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
return false;
}
-/* Invoke dstructors for CLOSURE (a struct link_map *). Called with
- exception handling temporarily disabled, to make errors fatal. */
-static void
-call_destructors (void *closure)
-{
- struct link_map *map = closure;
-
- if (map->l_info[DT_FINI_ARRAY] != NULL)
- {
- ElfW(Addr) *array =
- (ElfW(Addr) *) (map->l_addr
- + map->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
- unsigned int sz = (map->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
- / sizeof (ElfW(Addr)));
-
- while (sz-- > 0)
- ((fini_t) array[sz]) ();
- }
-
- /* Next try the old-style destructor. */
- if (map->l_info[DT_FINI] != NULL)
- DL_CALL_DT_FINI (map, ((void *) map->l_addr
- + map->l_info[DT_FINI]->d_un.d_ptr));
-}
-
void
_dl_close_worker (struct link_map *map, bool force)
{
@@ -279,17 +249,7 @@ _dl_close_worker (struct link_map *map, bool force)
half-cooked objects. Temporarily disable exception
handling, so that errors are fatal. */
if (imap->l_init_called)
- {
- /* When debugging print a message first. */
- if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS,
- 0))
- _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
- imap->l_name, nsid);
-
- if (imap->l_info[DT_FINI_ARRAY] != NULL
- || imap->l_info[DT_FINI] != NULL)
- _dl_catch_exception (NULL, call_destructors, imap);
- }
+ _dl_catch_exception (NULL, _dl_call_fini, imap);
#ifdef SHARED
/* Auditing checkpoint: we remove an object. */
diff --git a/elf/dl-fini.c b/elf/dl-fini.c
index e14259a3c8806e0d..2d34658d4c3a470c 100644
--- a/elf/dl-fini.c
+++ b/elf/dl-fini.c
@@ -20,11 +20,6 @@
#include <string.h>
#include <ldsodefs.h>
-
-/* Type of the constructor functions. */
-typedef void (*fini_t) (void);
-
-
void
_dl_fini (void)
{
@@ -115,38 +110,7 @@ _dl_fini (void)
if (l->l_init_called)
{
- /* Make sure nothing happens if we are called twice. */
- l->l_init_called = 0;
-
- /* Is there a destructor function? */
- if (l->l_info[DT_FINI_ARRAY] != NULL
- || l->l_info[DT_FINI] != NULL)
- {
- /* When debugging print a message first. */
- if (__builtin_expect (GLRO(dl_debug_mask)
- & DL_DEBUG_IMPCALLS, 0))
- _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
- DSO_FILENAME (l->l_name),
- ns);
-
- /* First see whether an array is given. */
- if (l->l_info[DT_FINI_ARRAY] != NULL)
- {
- ElfW(Addr) *array =
- (ElfW(Addr) *) (l->l_addr
- + l->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
- unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
- / sizeof (ElfW(Addr)));
- while (i-- > 0)
- ((fini_t) array[i]) ();
- }
-
- /* Next try the old-style destructor. */
- if (l->l_info[DT_FINI] != NULL)
- DL_CALL_DT_FINI
- (l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
- }
-
+ _dl_call_fini (l);
#ifdef SHARED
/* Auditing checkpoint: another object closed. */
_dl_audit_objclose (l);
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 29bbde3e83e37d7e..0bad34d44a5685d9 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -93,6 +93,9 @@ typedef struct link_map *lookup_t;
: (__glibc_unlikely ((ref)->st_shndx == SHN_ABS) ? 0 \
: LOOKUP_VALUE_ADDRESS (map, map_set)) + (ref)->st_value)
+/* Type of a constructor function, in DT_FINI, DT_FINI_ARRAY. */
+typedef void (*fini_t) (void);
+
/* On some architectures a pointer to a function is not just a pointer
to the actual code of the function but rather an architecture
specific descriptor. */
@@ -1047,6 +1050,11 @@ extern void _dl_init (struct link_map *main_map, int argc, char **argv,
initializer functions have completed. */
extern void _dl_fini (void) attribute_hidden;
+/* Invoke the DT_FINI_ARRAY and DT_FINI destructors for MAP, which
+ must be a struct link_map *. Can be used as an argument to
+ _dl_catch_exception. */
+void _dl_call_fini (void *map) attribute_hidden;
+
/* Sort array MAPS according to dependencies of the contained objects.
If FORCE_FIRST, MAPS[0] keeps its place even if the dependencies
say otherwise. */

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@ -0,0 +1,30 @@
commit f6c8204fd7fabf0cf4162eaf10ccf23258e4d10e
Author: Florian Weimer <fweimer@redhat.com>
Date: Tue Aug 22 13:56:25 2023 +0200
elf: Do not run constructors for proxy objects
Otherwise, the ld.so constructor runs for each audit namespace
and each dlmopen namespace.
diff --git a/elf/dl-init.c b/elf/dl-init.c
index 99ce531d7b326f5f..73c0259fbe6d19af 100644
--- a/elf/dl-init.c
+++ b/elf/dl-init.c
@@ -28,10 +28,14 @@ typedef void (*init_t) (int, char **, char **);
static void
call_init (struct link_map *l, int argc, char **argv, char **env)
{
+ /* Do not run constructors for proxy objects. */
+ if (l != l->l_real)
+ return;
+
/* If the object has not been relocated, this is a bug. The
function pointers are invalid in this case. (Executables do not
- need relocation, and neither do proxy objects.) */
- assert (l->l_real->l_relocated || l->l_real->l_type == lt_executable);
+ need relocation.) */
+ assert (l->l_relocated || l->l_type == lt_executable);
if (l->l_init_called)
/* This object is all done. */

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@ -0,0 +1,637 @@
commit 6985865bc3ad5b23147ee73466583dd7fdf65892
Author: Florian Weimer <fweimer@redhat.com>
Date: Fri Sep 8 12:32:14 2023 +0200
elf: Always call destructors in reverse constructor order (bug 30785)
The current implementation of dlclose (and process exit) re-sorts the
link maps before calling ELF destructors. Destructor order is not the
reverse of the constructor order as a result: The second sort takes
relocation dependencies into account, and other differences can result
from ambiguous inputs, such as cycles. (The force_first handling in
_dl_sort_maps is not effective for dlclose.) After the changes in
this commit, there is still a required difference due to
dlopen/dlclose ordering by the application, but the previous
discrepancies went beyond that.
A new global (namespace-spanning) list of link maps,
_dl_init_called_list, is updated right before ELF constructors are
called from _dl_init.
In dl_close_worker, the maps variable, an on-stack variable length
array, is eliminated. (VLAs are problematic, and dlclose should not
call malloc because it cannot readily deal with malloc failure.)
Marking still-used objects uses the namespace list directly, with
next and next_idx replacing the done_index variable.
After marking, _dl_init_called_list is used to call the destructors
of now-unused maps in reverse destructor order. These destructors
can call dlopen. Previously, new objects do not have l_map_used set.
This had to change: There is no copy of the link map list anymore,
so processing would cover newly opened (and unmarked) mappings,
unloading them. Now, _dl_init (indirectly) sets l_map_used, too.
(dlclose is handled by the existing reentrancy guard.)
After _dl_init_called_list traversal, two more loops follow. The
processing order changes to the original link map order in the
namespace. Previously, dependency order was used. The difference
should not matter because relocation dependencies could already
reorder link maps in the old code.
The changes to _dl_fini remove the sorting step and replace it with
a traversal of _dl_init_called_list. The l_direct_opencount
decrement outside the loader lock is removed because it appears
incorrect: the counter manipulation could race with other dynamic
loader operations.
tst-audit23 needs adjustments to the changes in LA_ACT_DELETE
notifications. The new approach for checking la_activity should
make it clearer that la_activty calls come in pairs around namespace
updates.
The dependency sorting test cases need updates because the destructor
order is always the opposite order of constructor order, even with
relocation dependencies or cycles present.
There is a future cleanup opportunity to remove the now-constant
force_first and for_fini arguments from the _dl_sort_maps function.
Fixes commit 1df71d32fe5f5905ffd5d100e5e9ca8ad62 ("elf: Implement
force_first handling in _dl_sort_maps_dfs (bug 28937)").
Reviewed-by: DJ Delorie <dj@redhat.com>
diff --git a/elf/dl-close.c b/elf/dl-close.c
index 26ea51dfbadc5b85..6b134f66628cfc03 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -137,30 +137,31 @@ _dl_close_worker (struct link_map *map, bool force)
bool any_tls = false;
const unsigned int nloaded = ns->_ns_nloaded;
- struct link_map *maps[nloaded];
- /* Run over the list and assign indexes to the link maps and enter
- them into the MAPS array. */
+ /* Run over the list and assign indexes to the link maps. */
int idx = 0;
for (struct link_map *l = ns->_ns_loaded; l != NULL; l = l->l_next)
{
l->l_map_used = 0;
l->l_map_done = 0;
l->l_idx = idx;
- maps[idx] = l;
++idx;
}
assert (idx == nloaded);
- /* Keep track of the lowest index link map we have covered already. */
- int done_index = -1;
- while (++done_index < nloaded)
+ /* Keep marking link maps until no new link maps are found. */
+ for (struct link_map *l = ns->_ns_loaded; l != NULL; )
{
- struct link_map *l = maps[done_index];
+ /* next is reset to earlier link maps for remarking. */
+ struct link_map *next = l->l_next;
+ int next_idx = l->l_idx + 1; /* next->l_idx, but covers next == NULL. */
if (l->l_map_done)
- /* Already handled. */
- continue;
+ {
+ /* Already handled. */
+ l = next;
+ continue;
+ }
/* Check whether this object is still used. */
if (l->l_type == lt_loaded
@@ -170,7 +171,10 @@ _dl_close_worker (struct link_map *map, bool force)
acquire is sufficient and correct. */
&& atomic_load_acquire (&l->l_tls_dtor_count) == 0
&& !l->l_map_used)
- continue;
+ {
+ l = next;
+ continue;
+ }
/* We need this object and we handle it now. */
l->l_map_used = 1;
@@ -197,8 +201,11 @@ _dl_close_worker (struct link_map *map, bool force)
already processed it, then we need to go back
and process again from that point forward to
ensure we keep all of its dependencies also. */
- if ((*lp)->l_idx - 1 < done_index)
- done_index = (*lp)->l_idx - 1;
+ if ((*lp)->l_idx < next_idx)
+ {
+ next = *lp;
+ next_idx = next->l_idx;
+ }
}
}
@@ -218,44 +225,65 @@ _dl_close_worker (struct link_map *map, bool force)
if (!jmap->l_map_used)
{
jmap->l_map_used = 1;
- if (jmap->l_idx - 1 < done_index)
- done_index = jmap->l_idx - 1;
+ if (jmap->l_idx < next_idx)
+ {
+ next = jmap;
+ next_idx = next->l_idx;
+ }
}
}
}
- }
- /* Sort the entries. We can skip looking for the binary itself which is
- at the front of the search list for the main namespace. */
- _dl_sort_maps (maps, nloaded, (nsid == LM_ID_BASE), true);
+ l = next;
+ }
- /* Call all termination functions at once. */
- bool unload_any = false;
- bool scope_mem_left = false;
- unsigned int unload_global = 0;
- unsigned int first_loaded = ~0;
- for (unsigned int i = 0; i < nloaded; ++i)
+ /* Call the destructors in reverse constructor order, and remove the
+ closed link maps from the list. */
+ for (struct link_map **init_called_head = &_dl_init_called_list;
+ *init_called_head != NULL; )
{
- struct link_map *imap = maps[i];
+ struct link_map *imap = *init_called_head;
- /* All elements must be in the same namespace. */
- assert (imap->l_ns == nsid);
-
- if (!imap->l_map_used)
+ /* _dl_init_called_list is global, to produce a global odering.
+ Ignore the other namespaces (and link maps that are still used). */
+ if (imap->l_ns != nsid || imap->l_map_used)
+ init_called_head = &imap->l_init_called_next;
+ else
{
assert (imap->l_type == lt_loaded && !imap->l_nodelete_active);
- /* Call its termination function. Do not do it for
- half-cooked objects. Temporarily disable exception
- handling, so that errors are fatal. */
- if (imap->l_init_called)
+ /* _dl_init_called_list is updated at the same time as
+ l_init_called. */
+ assert (imap->l_init_called);
+
+ if (imap->l_info[DT_FINI_ARRAY] != NULL
+ || imap->l_info[DT_FINI] != NULL)
_dl_catch_exception (NULL, _dl_call_fini, imap);
#ifdef SHARED
/* Auditing checkpoint: we remove an object. */
_dl_audit_objclose (imap);
#endif
+ /* Unlink this link map. */
+ *init_called_head = imap->l_init_called_next;
+ }
+ }
+
+
+ bool unload_any = false;
+ bool scope_mem_left = false;
+ unsigned int unload_global = 0;
+
+ /* For skipping un-unloadable link maps in the second loop. */
+ struct link_map *first_loaded = ns->_ns_loaded;
+ /* Iterate over the namespace to find objects to unload. Some
+ unloadable objects may not be on _dl_init_called_list due to
+ dlopen failure. */
+ for (struct link_map *imap = first_loaded; imap != NULL; imap = imap->l_next)
+ {
+ if (!imap->l_map_used)
+ {
/* This object must not be used anymore. */
imap->l_removed = 1;
@@ -266,8 +294,8 @@ _dl_close_worker (struct link_map *map, bool force)
++unload_global;
/* Remember where the first dynamically loaded object is. */
- if (i < first_loaded)
- first_loaded = i;
+ if (first_loaded == NULL)
+ first_loaded = imap;
}
/* Else imap->l_map_used. */
else if (imap->l_type == lt_loaded)
@@ -403,8 +431,8 @@ _dl_close_worker (struct link_map *map, bool force)
imap->l_loader = NULL;
/* Remember where the first dynamically loaded object is. */
- if (i < first_loaded)
- first_loaded = i;
+ if (first_loaded == NULL)
+ first_loaded = imap;
}
}
@@ -475,10 +503,11 @@ _dl_close_worker (struct link_map *map, bool force)
/* Check each element of the search list to see if all references to
it are gone. */
- for (unsigned int i = first_loaded; i < nloaded; ++i)
+ for (struct link_map *imap = first_loaded; imap != NULL; )
{
- struct link_map *imap = maps[i];
- if (!imap->l_map_used)
+ if (imap->l_map_used)
+ imap = imap->l_next;
+ else
{
assert (imap->l_type == lt_loaded);
@@ -686,7 +715,9 @@ _dl_close_worker (struct link_map *map, bool force)
if (imap == GL(dl_initfirst))
GL(dl_initfirst) = NULL;
+ struct link_map *next = imap->l_next;
free (imap);
+ imap = next;
}
}
diff --git a/elf/dl-fini.c b/elf/dl-fini.c
index 2d34658d4c3a470c..25a7767d707721d5 100644
--- a/elf/dl-fini.c
+++ b/elf/dl-fini.c
@@ -23,116 +23,68 @@
void
_dl_fini (void)
{
- /* Lots of fun ahead. We have to call the destructors for all still
- loaded objects, in all namespaces. The problem is that the ELF
- specification now demands that dependencies between the modules
- are taken into account. I.e., the destructor for a module is
- called before the ones for any of its dependencies.
-
- To make things more complicated, we cannot simply use the reverse
- order of the constructors. Since the user might have loaded objects
- using `dlopen' there are possibly several other modules with its
- dependencies to be taken into account. Therefore we have to start
- determining the order of the modules once again from the beginning. */
-
- /* We run the destructors of the main namespaces last. As for the
- other namespaces, we pick run the destructors in them in reverse
- order of the namespace ID. */
-#ifdef SHARED
- int do_audit = 0;
- again:
-#endif
- for (Lmid_t ns = GL(dl_nns) - 1; ns >= 0; --ns)
- {
- /* Protect against concurrent loads and unloads. */
- __rtld_lock_lock_recursive (GL(dl_load_lock));
-
- unsigned int nloaded = GL(dl_ns)[ns]._ns_nloaded;
- /* No need to do anything for empty namespaces or those used for
- auditing DSOs. */
- if (nloaded == 0
-#ifdef SHARED
- || GL(dl_ns)[ns]._ns_loaded->l_auditing != do_audit
-#endif
- )
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
- else
- {
+ /* Call destructors strictly in the reverse order of constructors.
+ This causes fewer surprises than some arbitrary reordering based
+ on new (relocation) dependencies. None of the objects are
+ unmapped, so applications can deal with this if their DSOs remain
+ in a consistent state after destructors have run. */
+
+ /* Protect against concurrent loads and unloads. */
+ __rtld_lock_lock_recursive (GL(dl_load_lock));
+
+ /* Ignore objects which are opened during shutdown. */
+ struct link_map *local_init_called_list = _dl_init_called_list;
+
+ for (struct link_map *l = local_init_called_list; l != NULL;
+ l = l->l_init_called_next)
+ /* Bump l_direct_opencount of all objects so that they
+ are not dlclose()ed from underneath us. */
+ ++l->l_direct_opencount;
+
+ /* After this point, everything linked from local_init_called_list
+ cannot be unloaded because of the reference counter update. */
+ __rtld_lock_unlock_recursive (GL(dl_load_lock));
+
+ /* Perform two passes: One for non-audit modules, one for audit
+ modules. This way, audit modules receive unload notifications
+ for non-audit objects, and the destructors for audit modules
+ still run. */
#ifdef SHARED
- _dl_audit_activity_nsid (ns, LA_ACT_DELETE);
+ int last_pass = GLRO(dl_naudit) > 0;
+ Lmid_t last_ns = -1;
+ for (int do_audit = 0; do_audit <= last_pass; ++do_audit)
#endif
-
- /* Now we can allocate an array to hold all the pointers and
- copy the pointers in. */
- struct link_map *maps[nloaded];
-
- unsigned int i;
- struct link_map *l;
- assert (nloaded != 0 || GL(dl_ns)[ns]._ns_loaded == NULL);
- for (l = GL(dl_ns)[ns]._ns_loaded, i = 0; l != NULL; l = l->l_next)
- /* Do not handle ld.so in secondary namespaces. */
- if (l == l->l_real)
- {
- assert (i < nloaded);
-
- maps[i] = l;
- l->l_idx = i;
- ++i;
-
- /* Bump l_direct_opencount of all objects so that they
- are not dlclose()ed from underneath us. */
- ++l->l_direct_opencount;
- }
- assert (ns != LM_ID_BASE || i == nloaded);
- assert (ns == LM_ID_BASE || i == nloaded || i == nloaded - 1);
- unsigned int nmaps = i;
-
- /* Now we have to do the sorting. We can skip looking for the
- binary itself which is at the front of the search list for
- the main namespace. */
- _dl_sort_maps (maps, nmaps, (ns == LM_ID_BASE), true);
-
- /* We do not rely on the linked list of loaded object anymore
- from this point on. We have our own list here (maps). The
- various members of this list cannot vanish since the open
- count is too high and will be decremented in this loop. So
- we release the lock so that some code which might be called
- from a destructor can directly or indirectly access the
- lock. */
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
-
- /* 'maps' now contains the objects in the right order. Now
- call the destructors. We have to process this array from
- the front. */
- for (i = 0; i < nmaps; ++i)
- {
- struct link_map *l = maps[i];
-
- if (l->l_init_called)
- {
- _dl_call_fini (l);
+ for (struct link_map *l = local_init_called_list; l != NULL;
+ l = l->l_init_called_next)
+ {
#ifdef SHARED
- /* Auditing checkpoint: another object closed. */
- _dl_audit_objclose (l);
+ if (GL(dl_ns)[l->l_ns]._ns_loaded->l_auditing != do_audit)
+ continue;
+
+ /* Avoid back-to-back calls of _dl_audit_activity_nsid for the
+ same namespace. */
+ if (last_ns != l->l_ns)
+ {
+ if (last_ns >= 0)
+ _dl_audit_activity_nsid (last_ns, LA_ACT_CONSISTENT);
+ _dl_audit_activity_nsid (l->l_ns, LA_ACT_DELETE);
+ last_ns = l->l_ns;
+ }
#endif
- }
- /* Correct the previous increment. */
- --l->l_direct_opencount;
- }
+ /* There is no need to re-enable exceptions because _dl_fini
+ is not called from a context where exceptions are caught. */
+ _dl_call_fini (l);
#ifdef SHARED
- _dl_audit_activity_nsid (ns, LA_ACT_CONSISTENT);
+ /* Auditing checkpoint: another object closed. */
+ _dl_audit_objclose (l);
#endif
- }
- }
+ }
#ifdef SHARED
- if (! do_audit && GLRO(dl_naudit) > 0)
- {
- do_audit = 1;
- goto again;
- }
+ if (last_ns >= 0)
+ _dl_audit_activity_nsid (last_ns, LA_ACT_CONSISTENT);
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_STATISTICS))
_dl_debug_printf ("\nruntime linker statistics:\n"
diff --git a/elf/dl-init.c b/elf/dl-init.c
index 73c0259fbe6d19af..eb6c83d180c3f1a1 100644
--- a/elf/dl-init.c
+++ b/elf/dl-init.c
@@ -24,6 +24,7 @@
/* Type of the initializer. */
typedef void (*init_t) (int, char **, char **);
+struct link_map *_dl_init_called_list;
static void
call_init (struct link_map *l, int argc, char **argv, char **env)
@@ -45,6 +46,21 @@ call_init (struct link_map *l, int argc, char **argv, char **env)
dependency. */
l->l_init_called = 1;
+ /* Help an already-running dlclose: The just-loaded object must not
+ be removed during the current pass. (No effect if no dlclose in
+ progress.) */
+ l->l_map_used = 1;
+
+ /* Record execution before starting any initializers. This way, if
+ the initializers themselves call dlopen, their ELF destructors
+ will eventually be run before this object is destructed, matching
+ that their ELF constructors have run before this object was
+ constructed. _dl_fini uses this list for audit callbacks, so
+ register objects on the list even if they do not have a
+ constructor. */
+ l->l_init_called_next = _dl_init_called_list;
+ _dl_init_called_list = l;
+
/* Check for object which constructors we do not run here. */
if (__builtin_expect (l->l_name[0], 'a') == '\0'
&& l->l_type == lt_executable)
diff --git a/elf/dso-sort-tests-1.def b/elf/dso-sort-tests-1.def
index 4bf9052db16fb352..61dc54f8ae06d465 100644
--- a/elf/dso-sort-tests-1.def
+++ b/elf/dso-sort-tests-1.def
@@ -53,21 +53,14 @@ tst-dso-ordering10: {}->a->b->c;soname({})=c
output: b>a>{}<a<b
# Complex example from Bugzilla #15311, under-linked and with circular
-# relocation(dynamic) dependencies. While this is technically unspecified, the
-# presumed reasonable practical behavior is for the destructor order to respect
-# the static DT_NEEDED links (here this means the a->b->c->d order).
-# The older dynamic_sort=1 algorithm does not achieve this, while the DFS-based
-# dynamic_sort=2 algorithm does, although it is still arguable whether going
-# beyond spec to do this is the right thing to do.
-# The below expected outputs are what the two algorithms currently produce
-# respectively, for regression testing purposes.
+# relocation(dynamic) dependencies. For both sorting algorithms, the
+# destruction order is the reverse of the construction order, and
+# relocation dependencies are not taken into account.
tst-bz15311: {+a;+e;+f;+g;+d;%d;-d;-g;-f;-e;-a};a->b->c->d;d=>[ba];c=>a;b=>e=>a;c=>f=>b;d=>g=>c
-output(glibc.rtld.dynamic_sort=1): {+a[d>c>b>a>];+e[e>];+f[f>];+g[g>];+d[];%d(b(e(a()))a()g(c(a()f(b(e(a()))))));-d[];-g[];-f[];-e[];-a[<a<c<d<g<f<b<e];}
-output(glibc.rtld.dynamic_sort=2): {+a[d>c>b>a>];+e[e>];+f[f>];+g[g>];+d[];%d(b(e(a()))a()g(c(a()f(b(e(a()))))));-d[];-g[];-f[];-e[];-a[<g<f<a<b<c<d<e];}
+output: {+a[d>c>b>a>];+e[e>];+f[f>];+g[g>];+d[];%d(b(e(a()))a()g(c(a()f(b(e(a()))))));-d[];-g[];-f[];-e[];-a[<g<f<e<a<b<c<d];}
# Test that even in the presence of dependency loops involving dlopen'ed
# object, that object is initialized last (and not unloaded prematurely).
-# Final destructor order is indeterminate due to the cycle.
+# Final destructor order is the opposite of constructor order.
tst-bz28937: {+a;+b;-b;+c;%c};a->a1;a->a2;a2->a;b->b1;c->a1;c=>a1
-output(glibc.rtld.dynamic_sort=1): {+a[a2>a1>a>];+b[b1>b>];-b[<b<b1];+c[c>];%c(a1());}<a<a2<c<a1
-output(glibc.rtld.dynamic_sort=2): {+a[a2>a1>a>];+b[b1>b>];-b[<b<b1];+c[c>];%c(a1());}<a2<a<c<a1
+output: {+a[a2>a1>a>];+b[b1>b>];-b[<b<b1];+c[c>];%c(a1());}<c<a<a1<a2
diff --git a/elf/tst-audit23.c b/elf/tst-audit23.c
index 4904cf1340a97ee1..f40760bd702e87c1 100644
--- a/elf/tst-audit23.c
+++ b/elf/tst-audit23.c
@@ -98,6 +98,8 @@ do_test (int argc, char *argv[])
char *lname;
uintptr_t laddr;
Lmid_t lmid;
+ uintptr_t cookie;
+ uintptr_t namespace;
bool closed;
} objs[max_objs] = { [0 ... max_objs-1] = { .closed = false } };
size_t nobjs = 0;
@@ -117,6 +119,9 @@ do_test (int argc, char *argv[])
size_t buffer_length = 0;
while (xgetline (&buffer, &buffer_length, out))
{
+ *strchrnul (buffer, '\n') = '\0';
+ printf ("info: subprocess output: %s\n", buffer);
+
if (startswith (buffer, "la_activity: "))
{
uintptr_t cookie;
@@ -125,29 +130,26 @@ do_test (int argc, char *argv[])
&cookie);
TEST_COMPARE (r, 2);
- /* The cookie identifies the object at the head of the link map,
- so we only add a new namespace if it changes from the previous
- one. This works since dlmopen is the last in the test body. */
- if (cookie != last_act_cookie && last_act_cookie != -1)
- TEST_COMPARE (last_act, LA_ACT_CONSISTENT);
-
if (this_act == LA_ACT_ADD && acts[nacts] != cookie)
{
+ /* The cookie identifies the object at the head of the
+ link map, so we only add a new namespace if it
+ changes from the previous one. This works since
+ dlmopen is the last in the test body. */
+ if (cookie != last_act_cookie && last_act_cookie != -1)
+ TEST_COMPARE (last_act, LA_ACT_CONSISTENT);
+
acts[nacts++] = cookie;
last_act_cookie = cookie;
}
- /* The LA_ACT_DELETE is called in the reverse order of LA_ACT_ADD
- at program termination (if the tests adds a dlclose or a library
- with extra dependencies this will need to be adapted). */
+ /* LA_ACT_DELETE is called multiple times for each
+ namespace, depending on destruction order. */
else if (this_act == LA_ACT_DELETE)
- {
- last_act_cookie = acts[--nacts];
- TEST_COMPARE (acts[nacts], cookie);
- acts[nacts] = 0;
- }
+ last_act_cookie = cookie;
else if (this_act == LA_ACT_CONSISTENT)
{
TEST_COMPARE (cookie, last_act_cookie);
+ last_act_cookie = -1;
/* LA_ACT_DELETE must always be followed by an la_objclose. */
if (last_act == LA_ACT_DELETE)
@@ -179,6 +181,8 @@ do_test (int argc, char *argv[])
objs[nobjs].lname = lname;
objs[nobjs].laddr = laddr;
objs[nobjs].lmid = lmid;
+ objs[nobjs].cookie = cookie;
+ objs[nobjs].namespace = last_act_cookie;
objs[nobjs].closed = false;
nobjs++;
@@ -201,6 +205,12 @@ do_test (int argc, char *argv[])
if (strcmp (lname, objs[i].lname) == 0 && lmid == objs[i].lmid)
{
TEST_COMPARE (objs[i].closed, false);
+ TEST_COMPARE (objs[i].cookie, cookie);
+ if (objs[i].namespace == -1)
+ /* No LA_ACT_ADD before the first la_objopen call. */
+ TEST_COMPARE (acts[0], last_act_cookie);
+ else
+ TEST_COMPARE (objs[i].namespace, last_act_cookie);
objs[i].closed = true;
break;
}
@@ -209,11 +219,7 @@ do_test (int argc, char *argv[])
/* la_objclose should be called after la_activity(LA_ACT_DELETE) for
the closed object's namespace. */
TEST_COMPARE (last_act, LA_ACT_DELETE);
- if (!seen_first_objclose)
- {
- TEST_COMPARE (last_act_cookie, cookie);
- seen_first_objclose = true;
- }
+ seen_first_objclose = true;
}
}
diff --git a/include/link.h b/include/link.h
index 041ff5f753a9ee11..a37b2cf3133eefd5 100644
--- a/include/link.h
+++ b/include/link.h
@@ -276,6 +276,10 @@ struct link_map
/* List of object in order of the init and fini calls. */
struct link_map **l_initfini;
+ /* Linked list of objects in reverse ELF constructor execution
+ order. Head of list is stored in _dl_init_called_list. */
+ struct link_map *l_init_called_next;
+
/* List of the dependencies introduced through symbol binding. */
struct link_map_reldeps
{
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 0bad34d44a5685d9..906447e677a4ca40 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -1046,6 +1046,10 @@ extern int _dl_check_map_versions (struct link_map *map, int verbose,
extern void _dl_init (struct link_map *main_map, int argc, char **argv,
char **env) attribute_hidden;
+/* List of ELF objects in reverse order of their constructor
+ invocation. */
+extern struct link_map *_dl_init_called_list attribute_hidden;
+
/* Call the finalizer functions of all shared objects whose
initializer functions have completed. */
extern void _dl_fini (void) attribute_hidden;

141
glibc-rh2233338-5.patch Normal file
View File

@ -0,0 +1,141 @@
commit 53df2ce6885da3d0e89e87dca7b095622296014f
Author: Florian Weimer <fweimer@redhat.com>
Date: Fri Sep 8 13:02:06 2023 +0200
elf: Remove unused l_text_end field from struct link_map
It is a left-over from commit 52a01100ad011293197637e42b5be1a479a2
("elf: Remove ad-hoc restrictions on dlopen callers [BZ #22787]").
When backporting commmit 6985865bc3ad5b23147ee73466583dd7fdf65892
("elf: Always call destructors in reverse constructor order
(bug 30785)"), we can move the l_init_called_next field to this
place, so that the internal GLIBC_PRIVATE ABI does not change.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Conflicts:
elf/dl-load.h
(Missing commit "Avoid "inline" after return type in function
definitions.")
elf/rtld.c
(Missing rtld_setup_main_map function. Re-did the l_text_end
removal from scratch.)
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 0b45e6e3db31c70d..52dc564af9e95878 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1176,7 +1176,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
/* Now process the load commands and map segments into memory.
This is responsible for filling in:
- l_map_start, l_map_end, l_addr, l_contiguous, l_text_end, l_phdr
+ l_map_start, l_map_end, l_addr, l_contiguous, l_phdr
*/
errstring = _dl_map_segments (l, fd, header, type, loadcmds, nloadcmds,
maplength, has_holes, loader);
diff --git a/elf/dl-load.h b/elf/dl-load.h
index 66ea2e9237ab6321..ebf2604e044c3bde 100644
--- a/elf/dl-load.h
+++ b/elf/dl-load.h
@@ -82,14 +82,11 @@ struct loadcmd
/* This is a subroutine of _dl_map_segments. It should be called for each
load command, some time after L->l_addr has been set correctly. It is
- responsible for setting up the l_text_end and l_phdr fields. */
-static void __always_inline
+ responsible for setting the l_phdr fields */
+static __always_inline void
_dl_postprocess_loadcmd (struct link_map *l, const ElfW(Ehdr) *header,
const struct loadcmd *c)
{
- if (c->prot & PROT_EXEC)
- l->l_text_end = l->l_addr + c->mapend;
-
if (l->l_phdr == 0
&& c->mapoff <= header->e_phoff
&& ((size_t) (c->mapend - c->mapstart + c->mapoff)
@@ -102,7 +99,7 @@ _dl_postprocess_loadcmd (struct link_map *l, const ElfW(Ehdr) *header,
/* This is a subroutine of _dl_map_object_from_fd. It is responsible
for filling in several fields in *L: l_map_start, l_map_end, l_addr,
- l_contiguous, l_text_end, l_phdr. On successful return, all the
+ l_contiguous, l_phdr. On successful return, all the
segments are mapped (or copied, or whatever) from the file into their
final places in the address space, with the correct page permissions,
and any bss-like regions already zeroed. It returns a null pointer
diff --git a/elf/rtld.c b/elf/rtld.c
index cd2cc4024a3581c2..c2edd0bfdc27f207 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -472,7 +472,6 @@ _dl_start_final (void *arg, struct dl_start_final_info *info)
GL(dl_rtld_map).l_real = &GL(dl_rtld_map);
GL(dl_rtld_map).l_map_start = (ElfW(Addr)) _begin;
GL(dl_rtld_map).l_map_end = (ElfW(Addr)) _end;
- GL(dl_rtld_map).l_text_end = (ElfW(Addr)) _etext;
/* Copy the TLS related data if necessary. */
#ifndef DONT_USE_BOOTSTRAP_MAP
# if NO_TLS_OFFSET != 0
@@ -1520,7 +1519,6 @@ dl_main (const ElfW(Phdr) *phdr,
}
main_map->l_map_end = 0;
- main_map->l_text_end = 0;
/* Perhaps the executable has no PT_LOAD header entries at all. */
main_map->l_map_start = ~0;
/* And it was opened directly. */
@@ -1591,8 +1589,6 @@ dl_main (const ElfW(Phdr) *phdr,
allocend = main_map->l_addr + ph->p_vaddr + ph->p_memsz;
if (main_map->l_map_end < allocend)
main_map->l_map_end = allocend;
- if ((ph->p_flags & PF_X) && allocend > main_map->l_text_end)
- main_map->l_text_end = allocend;
}
break;
@@ -1641,8 +1637,6 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
= (char *) main_map->l_tls_initimage + main_map->l_addr;
if (! main_map->l_map_end)
main_map->l_map_end = ~0;
- if (! main_map->l_text_end)
- main_map->l_text_end = ~0;
if (! GL(dl_rtld_map).l_libname && GL(dl_rtld_map).l_name)
{
/* We were invoked directly, so the program might not have a
diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h
index d2b35a080b57c183..352e992c578e416f 100644
--- a/elf/setup-vdso.h
+++ b/elf/setup-vdso.h
@@ -52,9 +52,6 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
l->l_addr = ph->p_vaddr;
if (ph->p_vaddr + ph->p_memsz >= l->l_map_end)
l->l_map_end = ph->p_vaddr + ph->p_memsz;
- if ((ph->p_flags & PF_X)
- && ph->p_vaddr + ph->p_memsz >= l->l_text_end)
- l->l_text_end = ph->p_vaddr + ph->p_memsz;
}
else
/* There must be no TLS segment. */
@@ -63,7 +60,6 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
l->l_map_start = (ElfW(Addr)) GLRO(dl_sysinfo_dso);
l->l_addr = l->l_map_start - l->l_addr;
l->l_map_end += l->l_addr;
- l->l_text_end += l->l_addr;
l->l_ld = (void *) ((ElfW(Addr)) l->l_ld + l->l_addr);
elf_get_dynamic_info (l, dyn_temp);
_dl_setup_hash (l);
diff --git a/include/link.h b/include/link.h
index a37b2cf3133eefd5..88683e7a747b86e0 100644
--- a/include/link.h
+++ b/include/link.h
@@ -251,8 +251,6 @@ struct link_map
/* Start and finish of memory map for this object. l_map_start
need not be the same as l_addr. */
ElfW(Addr) l_map_start, l_map_end;
- /* End of the executable part of the mapping. */
- ElfW(Addr) l_text_end;
/* Default array for 'l_scope'. */
struct r_scope_elem *l_scope_mem[4];

35
glibc-rh2233338-6.patch Normal file
View File

@ -0,0 +1,35 @@
commit d3ba6c1333b10680ce5900a628108507d9d4b844
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon Sep 11 09:17:52 2023 +0200
elf: Move l_init_called_next to old place of l_text_end in link map
This preserves all member offsets and the GLIBC_PRIVATE ABI
for backporting.
diff --git a/include/link.h b/include/link.h
index 88683e7a747b86e0..a464dd8e86cf89d0 100644
--- a/include/link.h
+++ b/include/link.h
@@ -252,6 +252,10 @@ struct link_map
need not be the same as l_addr. */
ElfW(Addr) l_map_start, l_map_end;
+ /* Linked list of objects in reverse ELF constructor execution
+ order. Head of list is stored in _dl_init_called_list. */
+ struct link_map *l_init_called_next;
+
/* Default array for 'l_scope'. */
struct r_scope_elem *l_scope_mem[4];
/* Size of array allocated for 'l_scope'. */
@@ -274,10 +278,6 @@ struct link_map
/* List of object in order of the init and fini calls. */
struct link_map **l_initfini;
- /* Linked list of objects in reverse ELF constructor execution
- order. Head of list is stored in _dl_init_called_list. */
- struct link_map *l_init_called_next;
-
/* List of the dependencies introduced through symbol binding. */
struct link_map_reldeps
{

11
glibc.spec
View File

@ -132,7 +132,7 @@ end \
Summary: The GNU libc libraries
Name: glibc
Version: %{glibcversion}
Release: %{glibcrelease}
Release: %{glibcrelease}.1
# In general, GPLv2+ is used by programs, LGPLv2+ is used for
# libraries.
@ -1047,6 +1047,12 @@ Patch854: glibc-rh2180462-1.patch
Patch855: glibc-rh2180462-2.patch
Patch856: glibc-rh2180462-3.patch
Patch857: glibc-rh2180462-4.patch
Patch858: glibc-rh2233338-1.patch
Patch859: glibc-rh2233338-2.patch
Patch860: glibc-rh2233338-3.patch
Patch861: glibc-rh2233338-4.patch
Patch862: glibc-rh2233338-5.patch
Patch863: glibc-rh2233338-6.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -2877,6 +2883,9 @@ fi
%files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
%changelog
* Mon Sep 11 2023 Florian Weimer <fweimer@redhat.com> - 2.28-236.1
- Always call destructors in reverse constructor order (#2233338)
* Tue Aug 15 2023 Carlos O'Donell <carlos@redhat.com> - 2.28-236
- Fix string and memory function tuning on small systems (#2180462)