elf: Call __libc_early_init for reused namespaces (bug 29528)

libc_map is never reset to NULL, neither during dlclose nor on a
dlopen call which reuses the namespace structure.  As a result, if a
namespace is reused, its libc is not initialized properly.  The most
visible result is a crash in the <ctype.h> functions.

To prevent similar bugs on namespace reuse from surfacing,
unconditionally initialize the chosen namespace to zero using memset.
This commit is contained in:
Florian Weimer 2022-08-26 21:15:43 +02:00
parent 06d4381dd8
commit d0e357ff45
5 changed files with 136 additions and 5 deletions

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@ -410,6 +410,7 @@ tests += \
tst-dlmopen4 \
tst-dlmopen-dlerror \
tst-dlmopen-gethostbyname \
tst-dlmopen-twice \
tst-dlopenfail \
tst-dlopenfail-2 \
tst-dlopenrpath \
@ -839,6 +840,8 @@ modules-names += \
tst-dlmopen1mod \
tst-dlmopen-dlerror-mod \
tst-dlmopen-gethostbyname-mod \
tst-dlmopen-twice-mod1 \
tst-dlmopen-twice-mod2 \
tst-dlopenfaillinkmod \
tst-dlopenfailmod1 \
tst-dlopenfailmod2 \
@ -2976,3 +2979,7 @@ $(objpfx)tst-audit-tlsdesc.out: $(objpfx)tst-auditmod-tlsdesc.so
tst-audit-tlsdesc-ENV = LD_AUDIT=$(objpfx)tst-auditmod-tlsdesc.so
$(objpfx)tst-audit-tlsdesc-dlopen.out: $(objpfx)tst-auditmod-tlsdesc.so
tst-audit-tlsdesc-dlopen-ENV = LD_AUDIT=$(objpfx)tst-auditmod-tlsdesc.so
$(objpfx)tst-dlmopen-twice.out: \
$(objpfx)tst-dlmopen-twice-mod1.so \
$(objpfx)tst-dlmopen-twice-mod2.so

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@ -844,11 +844,14 @@ _dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid,
_dl_signal_error (EINVAL, file, NULL, N_("\
no more namespaces available for dlmopen()"));
}
else if (nsid == GL(dl_nns))
{
__rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock);
++GL(dl_nns);
}
if (nsid == GL(dl_nns))
++GL(dl_nns);
/* Initialize the new namespace. Most members are
zero-initialized, only the lock needs special treatment. */
memset (&GL(dl_ns)[nsid], 0, sizeof (GL(dl_ns)[nsid]));
__rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock);
_dl_debug_update (nsid)->r_state = RT_CONSISTENT;
}

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@ -0,0 +1,37 @@
/* Initialization of libc after dlmopen/dlclose/dlmopen (bug 29528). Module 1.
Copyright (C) 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 <stdio.h>
static void __attribute__ ((constructor))
init (void)
{
puts ("info: tst-dlmopen-twice-mod1.so loaded");
fflush (stdout);
}
static void __attribute__ ((destructor))
fini (void)
{
puts ("info: tst-dlmopen-twice-mod1.so about to be unloaded");
fflush (stdout);
}
/* Large allocation. The second module does not have this, so it
should load libc at a different address. */
char large_allocate[16 * 1024 * 1024];

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@ -0,0 +1,50 @@
/* Initialization of libc after dlmopen/dlclose/dlmopen (bug 29528). Module 2.
Copyright (C) 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 <ctype.h>
#include <stdio.h>
static void __attribute__ ((constructor))
init (void)
{
puts ("info: tst-dlmopen-twice-mod2.so loaded");
fflush (stdout);
}
static void __attribute__ ((destructor))
fini (void)
{
puts ("info: tst-dlmopen-twice-mod2.so about to be unloaded");
fflush (stdout);
}
int
run_check (void)
{
puts ("info: about to call isalpha");
fflush (stdout);
volatile char ch = 'a';
if (!isalpha (ch))
{
puts ("error: isalpha ('a') is not true");
fflush (stdout);
return 1;
}
return 0;
}

34
elf/tst-dlmopen-twice.c Normal file
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@ -0,0 +1,34 @@
/* Initialization of libc after dlmopen/dlclose/dlmopen (bug 29528). Main.
Copyright (C) 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 <support/xdlfcn.h>
#include <support/check.h>
static int
do_test (void)
{
void *handle = xdlmopen (LM_ID_NEWLM, "tst-dlmopen-twice-mod1.so", RTLD_NOW);
xdlclose (handle);
handle = xdlmopen (LM_ID_NEWLM, "tst-dlmopen-twice-mod2.so", RTLD_NOW);
int (*run_check) (void) = xdlsym (handle, "run_check");
TEST_COMPARE (run_check (), 0);
xdlclose (handle);
return 0;
}
#include <support/test-driver.c>