elf: Fix DTV gap reuse logic (BZ #27135)

This is updated version of the 572bd547d5 (reverted by 40ebfd016a)
that fixes the _dl_next_tls_modid issues.

This issue with 572bd547d5 patch is the DTV entry will be only
update on dl_open_worker() with the update_tls_slotinfo() call after
all dependencies are being processed by _dl_map_object_deps().  However
_dl_map_object_deps() itself might call _dl_next_tls_modid(), and since
the _dl_tls_dtv_slotinfo_list::map is not yet set the entry will be
wrongly reused.

This patch fixes by renaming the _dl_next_tls_modid() function to
_dl_assign_tls_modid() and by passing the link_map so it can set
the slotinfo value so a subsequente _dl_next_tls_modid() call will
see the entry as allocated.

The intermediary value is cleared up on remove_slotinfo() for the case
a library fails to load with RTLD_NOW.

This patch fixes BZ #27135.

Checked on x86_64-linux-gnu.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
This commit is contained in:
Adhemerval Zanella 2021-06-25 10:54:12 -03:00
parent 0e1f068108
commit ba33937be2
8 changed files with 349 additions and 33 deletions

View File

@ -253,6 +253,13 @@ one-hundred = $(foreach x,0 1 2 3 4 5 6 7 8 9, \
0$x 1$x 2$x 3$x 4$x 5$x 6$x 7$x 8$x 9$x)
tst-tls-many-dynamic-modules := \
$(foreach n,$(one-hundred),tst-tls-manydynamic$(n)mod)
tst-tls-many-dynamic-modules-dep-suffixes = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 \
14 15 16 17 18 19
tst-tls-many-dynamic-modules-dep = \
$(foreach n,$(tst-tls-many-dynamic-modules-dep-suffixes),tst-tls-manydynamic$(n)mod-dep)
tst-tls-many-dynamic-modules-dep-bad-suffixes = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
tst-tls-many-dynamic-modules-dep-bad = \
$(foreach n,$(tst-tls-many-dynamic-modules-dep-bad-suffixes),tst-tls-manydynamic$(n)mod-dep-bad)
extra-test-objs += $(tlsmod17a-modules:=.os) $(tlsmod18a-modules:=.os) \
tst-tlsalign-vars.o
test-extras += tst-tlsmod17a tst-tlsmod18a tst-tlsalign-vars
@ -325,6 +332,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-audit11mod1 tst-audit11mod2 tst-auditmod11 \
tst-audit12mod1 tst-audit12mod2 tst-audit12mod3 tst-auditmod12 \
tst-latepthreadmod $(tst-tls-many-dynamic-modules) \
$(tst-tls-many-dynamic-modules-dep) \
$(tst-tls-many-dynamic-modules-dep-bad) \
tst-nodelete-dlclose-dso tst-nodelete-dlclose-plugin \
tst-main1mod tst-absolute-sym-lib \
tst-absolute-zero-lib tst-big-note-lib tst-unwind-ctor-lib \
@ -1812,10 +1821,63 @@ $(objpfx)tst-rtld-help.out: $(objpfx)ld.so
$(evaluate-test)
# Reuses tst-tls-many-dynamic-modules
$(patsubst %,$(objpfx)%.os,$(tst-tls-many-dynamic-modules-dep)): \
$(objpfx)tst-tls-manydynamic%mod-dep.os : tst-tls-manydynamicmod.c
$(compile-command.c) \
-DNAME=tls_global_$* -DSETTER=set_value_$* -DGETTER=get_value_$*
$(patsubst %,$(objpfx)%.os,$(tst-tls-many-dynamic-modules-dep-bad)): \
$(objpfx)tst-tls-manydynamic%mod-dep-bad.os : tst-tls-manydynamicmod.c
$(compile-command.c) \
-DNAME=tls_global_$* -DSETTER=set_value_$* -DGETTER=get_value_$*
tst-tls20mod-bad.so-no-z-defs = yes
# Single dependency.
$(objpfx)tst-tls-manydynamic0mod-dep.so: $(objpfx)tst-tls-manydynamic1mod-dep.so
# Double dependencies.
$(objpfx)tst-tls-manydynamic2mod-dep.so: $(objpfx)tst-tls-manydynamic3mod-dep.so \
$(objpfx)tst-tls-manydynamic4mod-dep.so
# Double dependencies with each dependency depent of another module.
$(objpfx)tst-tls-manydynamic5mod-dep.so: $(objpfx)tst-tls-manydynamic6mod-dep.so \
$(objpfx)tst-tls-manydynamic7mod-dep.so
$(objpfx)tst-tls-manydynamic6mod-dep.so: $(objpfx)tst-tls-manydynamic8mod-dep.so
$(objpfx)tst-tls-manydynamic7mod-dep.so: $(objpfx)tst-tls-manydynamic8mod-dep.so
# Long chain with one double dependency in the middle
$(objpfx)tst-tls-manydynamic9mod-dep.so: $(objpfx)tst-tls-manydynamic10mod-dep.so \
$(objpfx)tst-tls-manydynamic11mod-dep.so
$(objpfx)tst-tls-manydynamic10mod-dep.so: $(objpfx)tst-tls-manydynamic12mod-dep.so
$(objpfx)tst-tls-manydynamic12mod-dep.so: $(objpfx)tst-tls-manydynamic13mod-dep.so
# Long chain with two double depedencies in the middle
$(objpfx)tst-tls-manydynamic14mod-dep.so: $(objpfx)tst-tls-manydynamic15mod-dep.so
$(objpfx)tst-tls-manydynamic15mod-dep.so: $(objpfx)tst-tls-manydynamic16mod-dep.so \
$(objpfx)tst-tls-manydynamic17mod-dep.so
$(objpfx)tst-tls-manydynamic16mod-dep.so: $(objpfx)tst-tls-manydynamic18mod-dep.so \
$(objpfx)tst-tls-manydynamic19mod-dep.so
# Same but with an invalid module.
# Single dependency.
$(objpfx)tst-tls-manydynamic0mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
# Double dependencies.
$(objpfx)tst-tls-manydynamic1mod-dep-bad.so: $(objpfx)tst-tls-manydynamic2mod-dep-bad.so \
$(objpfx)tst-tls20mod-bad.so
# Double dependencies with each dependency depent of another module.
$(objpfx)tst-tls-manydynamic3mod-dep-bad.so: $(objpfx)tst-tls-manydynamic4mod-dep-bad.so \
$(objpfx)tst-tls-manydynamic5mod-dep-bad.so
$(objpfx)tst-tls-manydynamic4mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
$(objpfx)tst-tls-manydynamic5mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
# Long chain with one double dependency in the middle
$(objpfx)tst-tls-manydynamic6mod-dep-bad.so: $(objpfx)tst-tls-manydynamic7mod-dep-bad.so \
$(objpfx)tst-tls-manydynamic8mod-dep-bad.so
$(objpfx)tst-tls-manydynamic7mod-dep-bad.so: $(objpfx)tst-tls-manydynamic9mod-dep-bad.so
$(objpfx)tst-tls-manydynamic9mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
# Long chain with two double depedencies in the middle
$(objpfx)tst-tls-manydynamic10mod-dep-bad.so: $(objpfx)tst-tls-manydynamic11mod-dep-bad.so
$(objpfx)tst-tls-manydynamic11mod-dep-bad.so: $(objpfx)tst-tls-manydynamic12mod-dep-bad.so \
$(objpfx)tst-tls-manydynamic13mod-dep-bad.so
$(objpfx)tst-tls-manydynamic12mod-dep-bad.so: $(objpfx)tst-tls-manydynamic14mod-dep-bad.so \
$(objpfx)tst-tls20mod-bad.so
$(objpfx)tst-tls20: $(shared-thread-library)
$(objpfx)tst-tls20.out: $(objpfx)tst-tls20mod-bad.so \
$(tst-tls-many-dynamic-modules:%=$(objpfx)%.so)
$(tst-tls-many-dynamic-modules:%=$(objpfx)%.so) \
$(tst-tls-many-dynamic-modules-dep:%=$(objpfx)%.so) \
$(tst-tls-many-dynamic-modules-dep-bad:%=$(objpfx)%.so) \
# Reuses tst-tls-many-dynamic-modules
$(objpfx)tst-tls21: $(shared-thread-library)

View File

@ -77,8 +77,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
object that wasn't fully set up. */
if (__glibc_likely (old_map != NULL))
{
assert (old_map->l_tls_modid == idx);
/* Mark the entry as unused. These can be read concurrently. */
atomic_store_relaxed (&listp->slotinfo[idx - disp].gen,
GL(dl_tls_generation) + 1);
@ -88,7 +86,11 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
/* If this is not the last currently used entry no need to look
further. */
if (idx != GL(dl_tls_max_dtv_idx))
return true;
{
/* There is an unused dtv entry in the middle. */
GL(dl_tls_dtv_gaps) = true;
return true;
}
}
while (idx - disp > (disp == 0 ? 1 + GL(dl_tls_static_nelem) : 0))

View File

@ -1498,7 +1498,7 @@ cannot enable executable stack as shared object requires");
not set up TLS data structures, so don't use them now. */
|| __glibc_likely (GL(dl_tls_dtv_slotinfo_list) != NULL)))
/* Assign the next available module ID. */
l->l_tls_modid = _dl_next_tls_modid ();
_dl_assign_tls_modid (l);
#ifdef DL_AFTER_LOAD
DL_AFTER_LOAD (l);

View File

@ -899,16 +899,6 @@ no more namespaces available for dlmopen()"));
state if relocation failed, for example. */
if (args.map)
{
/* Maybe some of the modules which were loaded use TLS.
Since it will be removed in the following _dl_close call
we have to mark the dtv array as having gaps to fill the
holes. This is a pessimistic assumption which won't hurt
if not true. There is no need to do this when we are
loading the auditing DSOs since TLS has not yet been set
up. */
if ((mode & __RTLD_AUDIT) == 0)
GL(dl_tls_dtv_gaps) = true;
_dl_close_worker (args.map, true);
/* All l_nodelete_pending objects should have been deleted

View File

@ -126,8 +126,8 @@ oom (void)
}
size_t
_dl_next_tls_modid (void)
void
_dl_assign_tls_modid (struct link_map *l)
{
size_t result;
@ -157,7 +157,11 @@ _dl_next_tls_modid (void)
}
if (result - disp < runp->len)
break;
{
/* Mark the entry as used, so any dependency see it. */
atomic_store_relaxed (&runp->slotinfo[result - disp].map, l);
break;
}
disp += runp->len;
}
@ -184,17 +188,14 @@ _dl_next_tls_modid (void)
atomic_store_relaxed (&GL(dl_tls_max_dtv_idx), result);
}
return result;
l->l_tls_modid = result;
}
size_t
_dl_count_modids (void)
{
/* It is rare that we have gaps; see elf/dl-open.c (_dl_open) where
we fail to load a module and unload it leaving a gap. If we don't
have gaps then the number of modids is the current maximum so
return that. */
/* The count is the max unless dlclose or failed dlopen created gaps. */
if (__glibc_likely (!GL(dl_tls_dtv_gaps)))
return GL(dl_tls_max_dtv_idx);

View File

@ -1721,7 +1721,7 @@ dl_main (const ElfW(Phdr) *phdr,
/* Add the dynamic linker to the TLS list if it also uses TLS. */
if (GL(dl_rtld_map).l_tls_blocksize != 0)
/* Assign a module ID. Do this before loading any audit modules. */
GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
_dl_assign_tls_modid (&GL(dl_rtld_map));
audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_AUDIT);
audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_DEPAUDIT);

View File

@ -16,12 +16,14 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <array_length.h>
#include <dlfcn.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <support/check.h>
#include <support/support.h>
#include <support/test-driver.h>
#include <support/xdlfcn.h>
#include <support/xthread.h>
@ -59,28 +61,75 @@ access (int i)
char *buf = xasprintf ("tls_global_%02d", i);
dlerror ();
int *p = dlsym (mod[i], buf);
printf ("mod[%d]: &tls = %p\n", i, p);
if (test_verbose)
printf ("mod[%d]: &tls = %p\n", i, p);
if (p == NULL)
FAIL_EXIT1 ("dlsym failed: %s\n", dlerror ());
TEST_COMPARE (*p, 0);
++*p;
free (buf);
}
static void
access_mod (const char *modname, void *mod, int i)
{
char *modsym = xasprintf ("tls_global_%d", i);
dlerror ();
int *p = dlsym (mod, modsym);
if (test_verbose)
printf ("%s: &tls = %p\n", modname, p);
if (p == NULL)
FAIL_EXIT1 ("dlsym failed: %s\n", dlerror ());
TEST_COMPARE (*p, 0);
++*p;
free (modsym);
}
static void
access_dep (int i)
{
char *modname = xasprintf ("tst-tls-manydynamic%dmod-dep.so", i);
void *moddep = xdlopen (modname, RTLD_LAZY);
access_mod (modname, moddep, i);
free (modname);
xdlclose (moddep);
}
struct start_args
{
const char *modname;
void *mod;
int modi;
int ndeps;
const int *deps;
};
static void *
start (void *a)
{
struct start_args *args = a;
for (int i = 0; i < NMOD; i++)
if (mod[i] != NULL)
access (i);
if (args != NULL)
{
access_mod (args->modname, args->mod, args->modi);
for (int n = 0; n < args->ndeps; n++)
access_dep (args->deps[n]);
}
return 0;
}
static int
do_test (void)
/* This test gaps with shared libraries with dynamic TLS that has no
dependencies. The DTV gap is set with by trying to load an invalid
module, the entry should be used on the dlopen. */
static void
do_test_no_depedency (void)
{
int i;
for (i = 0; i < NMOD; i++)
for (int i = 0; i < NMOD; i++)
{
load_mod (i);
/* Bump the generation of mod[0] without using new dtv slot. */
@ -91,8 +140,220 @@ do_test (void)
pthread_t t = xpthread_create (0, start, 0);
xpthread_join (t);
}
for (i = 0; i < NMOD; i++)
for (int i = 0; i < NMOD; i++)
unload_mod (i);
}
/* The following test check DTV gaps handling with shared libraries that has
dependencies. It defines 5 different sets:
1. Single dependency:
mod0 -> mod1
2. Double dependency:
mod2 -> [mod3,mod4]
3. Double dependency with each dependency depent of another module:
mod5 -> [mod6,mod7] -> mod8
4. Long chain with one double dependency in the middle:
mod9 -> [mod10, mod11] -> mod12 -> mod13
5. Long chain with two double depedencies in the middle:
mod14 -> mod15 -> [mod16, mod17]
mod15 -> [mod18, mod19]
This does not cover all the possible gaps and configuration, but it
should check if different dynamic shared sets are placed correctly in
different gaps configurations. */
static int
nmodules (uint32_t v)
{
unsigned int r = 0;
while (v >>= 1)
r++;
return r + 1;
}
static inline bool
is_mod_set (uint32_t g, uint32_t n)
{
return (1U << (n - 1)) & g;
}
static void
print_gap (uint32_t g)
{
if (!test_verbose)
return;
printf ("gap: ");
int nmods = nmodules (g);
for (int n = 1; n <= nmods; n++)
printf ("%c", ((1 << (n - 1)) & g) == 0 ? 'G' : 'M');
printf ("\n");
}
static void
do_test_dependency (void)
{
/* Maps the module and its dependencies, use thread to access the TLS on
each loaded module. */
static const int tlsmanydeps0[] = { 1 };
static const int tlsmanydeps1[] = { 3, 4 };
static const int tlsmanydeps2[] = { 6, 7, 8 };
static const int tlsmanydeps3[] = { 10, 11, 12 };
static const int tlsmanydeps4[] = { 15, 16, 17, 18, 19 };
static const struct tlsmanydeps_t
{
int modi;
int ndeps;
const int *deps;
} tlsmanydeps[] =
{
{ 0, array_length (tlsmanydeps0), tlsmanydeps0 },
{ 2, array_length (tlsmanydeps1), tlsmanydeps1 },
{ 5, array_length (tlsmanydeps2), tlsmanydeps2 },
{ 9, array_length (tlsmanydeps3), tlsmanydeps3 },
{ 14, array_length (tlsmanydeps4), tlsmanydeps4 },
};
/* The gap configuration is defined as a bitmap: the bit set represents a
loaded module prior the tests execution, while a bit unsed is a module
unloaded. Not all permtation will show gaps, but it is simpler than
define each one independently. */
for (uint32_t g = 0; g < 64; g++)
{
print_gap (g);
int nmods = nmodules (g);
int mods[nmods];
/* We use '0' as indication for a gap, to avoid the dlclose on iteration
cleanup. */
for (int n = 1; n <= nmods; n++)
{
load_mod (n);
mods[n] = n;
}
for (int n = 1; n <= nmods; n++)
{
if (!is_mod_set (g, n))
{
unload_mod (n);
mods[n] = 0;
}
}
for (int t = 0; t < array_length (tlsmanydeps); t++)
{
char *moddepname = xasprintf ("tst-tls-manydynamic%dmod-dep.so",
tlsmanydeps[t].modi);
void *moddep = xdlopen (moddepname, RTLD_LAZY);
/* Access TLS in all loaded modules. */
struct start_args args =
{
moddepname,
moddep,
tlsmanydeps[t].modi,
tlsmanydeps[t].ndeps,
tlsmanydeps[t].deps
};
pthread_t t = xpthread_create (0, start, &args);
xpthread_join (t);
free (moddepname);
xdlclose (moddep);
}
for (int n = 1; n <= nmods; n++)
if (mods[n] != 0)
unload_mod (n);
}
}
/* The following test check DTV gaps handling with shared libraries that has
invalid dependencies. It defines 5 different sets:
1. Single dependency:
mod0 -> invalid
2. Double dependency:
mod1 -> [mod2,invalid]
3. Double dependency with each dependency depent of another module:
mod3 -> [mod4,mod5] -> invalid
4. Long chain with one double dependency in the middle:
mod6 -> [mod7, mod8] -> mod12 -> invalid
5. Long chain with two double depedencies in the middle:
mod10 -> mod11 -> [mod12, mod13]
mod12 -> [mod14, invalid]
This does not cover all the possible gaps and configuration, but it
should check if different dynamic shared sets are placed correctly in
different gaps configurations. */
static void
do_test_invalid_dependency (bool bind_now)
{
static const int tlsmanydeps[] = { 0, 1, 3, 6, 10 };
/* The gap configuration is defined as a bitmap: the bit set represents a
loaded module prior the tests execution, while a bit unsed is a module
unloaded. Not all permtation will show gaps, but it is simpler than
define each one independently. */
for (uint32_t g = 0; g < 64; g++)
{
print_gap (g);
int nmods = nmodules (g);
int mods[nmods];
/* We use '0' as indication for a gap, to avoid the dlclose on iteration
cleanup. */
for (int n = 1; n <= nmods; n++)
{
load_mod (n);
mods[n] = n;
}
for (int n = 1; n <= nmods; n++)
{
if (!is_mod_set (g, n))
{
unload_mod (n);
mods[n] = 0;
}
}
for (int t = 0; t < array_length (tlsmanydeps); t++)
{
char *moddepname = xasprintf ("tst-tls-manydynamic%dmod-dep-bad.so",
tlsmanydeps[t]);
void *moddep;
if (bind_now)
{
moddep = dlopen (moddepname, RTLD_NOW);
TEST_VERIFY (moddep == 0);
}
else
moddep = dlopen (moddepname, RTLD_LAZY);
/* Access TLS in all loaded modules. */
pthread_t t = xpthread_create (0, start, NULL);
xpthread_join (t);
free (moddepname);
if (!bind_now)
xdlclose (moddep);
}
for (int n = 1; n <= nmods; n++)
if (mods[n] != 0)
unload_mod (n);
}
}
static int
do_test (void)
{
do_test_no_depedency ();
do_test_dependency ();
do_test_invalid_dependency (true);
do_test_invalid_dependency (false);
return 0;
}

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@ -1171,8 +1171,8 @@ extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
extern void _dl_sysdep_start_cleanup (void) attribute_hidden;
/* Determine next available module ID. */
extern size_t _dl_next_tls_modid (void) attribute_hidden;
/* Determine next available module ID and set the L l_tls_modid. */
extern void _dl_assign_tls_modid (struct link_map *l) attribute_hidden;
/* Count the modules with TLS segments. */
extern size_t _dl_count_modids (void) attribute_hidden;