mirror/glibc
2
0
Fork 0
mirror of git://sourceware.org/git/glibc.git synced 2025-04-18 14:30:43 +08:00
Code Issues Packages Projects Releases Wiki Activity

Revert "elf: Always call destructors in reverse constructor order (bug 30785)"

Browse Source 
This reverts commit 5d83a52a4905405792418d6a0f3afa3601a98c37.

Reason for revert: Incompatibility with existing applications.
This commit is contained in:
Florian Weimer 2023-10-18 14:31:02 +02:00
parent ad96b55325
commit dc3b5b9048
7 changed files with 172 additions and 175 deletions

1
NEWS

@ -84,7 +84,6 @@ The following bugs are resolved with this release:
[30305] x86_64: Fix asm constraints in feraiseexcept
[30477] libc: [RISCV]: time64 does not work on riscv32
[30515] _dl_find_object incorrectly returns 1 during early startup
[30785] Always call destructors in reverse constructor order
[30804] F_GETLK, F_SETLK, and F_SETLKW value change for powerpc64 with
-D_FILE_OFFSET_BITS=64
[30842] Stack read overflow in getaddrinfo in no-aaaa mode (CVE-2023-4527)

115
elf/dl-close.c

@ -138,31 +138,30 @@ _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. */
/* Run over the list and assign indexes to the link maps and enter
them into the MAPS array. */
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 marking link maps until no new link maps are found. */
for (struct link_map *l = ns->_ns_loaded; l != NULL; )
/* Keep track of the lowest index link map we have covered already. */
int done_index = -1;
while (++done_index < nloaded)
{
/* 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. */
struct link_map *l = maps[done_index];
if (l->l_map_done)
{
/* Already handled. */
l = next;
continue;
}
/* Already handled. */
continue;
/* Check whether this object is still used. */
if (l->l_type == lt_loaded
@ -172,10 +171,7 @@ _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)
{
l = next;
continue;
}
continue;
/* We need this object and we handle it now. */
l->l_map_used = 1;
@ -202,11 +198,8 @@ _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 < next_idx)
{
next = *lp;
next_idx = next->l_idx;
}
if ((*lp)->l_idx - 1 < done_index)
done_index = (*lp)->l_idx - 1;
}
}
@ -226,65 +219,44 @@ _dl_close_worker (struct link_map *map, bool force)
if (!jmap->l_map_used)
{
jmap->l_map_used = 1;
if (jmap->l_idx < next_idx)
{
next = jmap;
next_idx = next->l_idx;
}
if (jmap->l_idx - 1 < done_index)
done_index = jmap->l_idx - 1;
}
}
}
l = next;
}
/* 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 = *init_called_head;
/* 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);
/* _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
/* 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)
{
struct link_map *imap = maps[i];
/* All elements must be in the same namespace. */
assert (imap->l_ns == nsid);
if (!imap->l_map_used)
{
assert (imap->l_type == lt_loaded && !imap->l_nodelete_active);
/* _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)
/* 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_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;
@ -295,8 +267,8 @@ _dl_close_worker (struct link_map *map, bool force)
++unload_global;
/* Remember where the first dynamically loaded object is. */
if (first_loaded == NULL)
first_loaded = imap;
if (i < first_loaded)
first_loaded = i;
}
/* Else imap->l_map_used. */
else if (imap->l_type == lt_loaded)
@ -432,8 +404,8 @@ _dl_close_worker (struct link_map *map, bool force)
imap->l_loader = NULL;
/* Remember where the first dynamically loaded object is. */
if (first_loaded == NULL)
first_loaded = imap;
if (i < first_loaded)
first_loaded = i;
}
}
@ -504,11 +476,10 @@ _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 (struct link_map *imap = first_loaded; imap != NULL; )
for (unsigned int i = first_loaded; i < nloaded; ++i)
{
if (imap->l_map_used)
imap = imap->l_next;
else
struct link_map *imap = maps[i];
if (!imap->l_map_used)
{
assert (imap->l_type == lt_loaded);
@ -719,9 +690,7 @@ _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;
}
}

148
elf/dl-fini.c

@ -24,68 +24,116 @@
void
_dl_fini (void)
{
/* 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. */
/* 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.
/* Protect against concurrent loads and unloads. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
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. */
/* 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. */
/* 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 last_pass = GLRO(dl_naudit) > 0;
Lmid_t last_ns = -1;
for (int do_audit = 0; do_audit <= last_pass; ++do_audit)
int do_audit = 0;
again:
#endif
for (struct link_map *l = local_init_called_list; l != NULL;
l = l->l_init_called_next)
{
#ifdef SHARED
if (GL(dl_ns)[l->l_ns]._ns_loaded->l_auditing != do_audit)
continue;
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));
/* 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;
}
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
{
#ifdef SHARED
_dl_audit_activity_nsid (ns, LA_ACT_DELETE);
#endif
/* 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);
/* 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);
#ifdef SHARED
/* Auditing checkpoint: another object closed. */
_dl_audit_objclose (l);
/* Auditing checkpoint: another object closed. */
_dl_audit_objclose (l);
#endif
}
}
/* Correct the previous increment. */
--l->l_direct_opencount;
}
#ifdef SHARED
if (last_ns >= 0)
_dl_audit_activity_nsid (last_ns, LA_ACT_CONSISTENT);
_dl_audit_activity_nsid (ns, LA_ACT_CONSISTENT);
#endif
}
}
#ifdef SHARED
if (! do_audit && GLRO(dl_naudit) > 0)
{
do_audit = 1;
goto again;
}
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_STATISTICS))
_dl_debug_printf ("\nruntime linker statistics:\n"

16
elf/dl-init.c

@ -21,7 +21,6 @@
#include <ldsodefs.h>
#include <elf-initfini.h>
struct link_map *_dl_init_called_list;
static void
call_init (struct link_map *l, int argc, char **argv, char **env)
@ -43,21 +42,6 @@ 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)

19
elf/dso-sort-tests-1.def

@ -53,14 +53,21 @@ 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. For both sorting algorithms, the
# destruction order is the reverse of the construction order, and
# relocation dependencies are not taken into account.
# 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.
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: {+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];}
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];}
# 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 the opposite of constructor order.
# Final destructor order is indeterminate due to the cycle.
tst-bz28937: {+a;+b;-b;+c;%c};a->a1;a->a2;a2->a;b->b1;c->a1;c=>a1
output: {+a[a2>a1>a>];+b[b1>b>];-b[<b<b1];+c[c>];%c(a1());}<c<a<a1<a2
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

44
elf/tst-audit23.c

@ -98,8 +98,6 @@ 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;
@ -119,9 +117,6 @@ 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;
@ -130,26 +125,29 @@ 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;
}
/* LA_ACT_DELETE is called multiple times for each
namespace, depending on destruction order. */
/* 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). */
else if (this_act == LA_ACT_DELETE)
last_act_cookie = cookie;
{
last_act_cookie = acts[--nacts];
TEST_COMPARE (acts[nacts], cookie);
acts[nacts] = 0;
}
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)
@ -181,8 +179,6 @@ 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++;
@ -205,12 +201,6 @@ 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;
}
@ -219,7 +209,11 @@ 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);
seen_first_objclose = true;
if (!seen_first_objclose)
{
TEST_COMPARE (last_act_cookie, cookie);
seen_first_objclose = true;
}
}
}

4
sysdeps/generic/ldsodefs.h

@ -1047,10 +1047,6 @@ 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;