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elf: Do not completely clear reused namespace in dlmopen (bug 29600)

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The data in the _ns_debug member must be preserved, otherwise
_dl_debug_initialize enters an infinite loop.  To be conservative,
only clear the libc_map member for now, to fix bug 29528.

Fixes commit d0e357ff45
("elf: Call __libc_early_init for reused namespaces (bug 29528)"),
by reverting most of it.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer 2022-10-14 11:02:25 +02:00
parent 15a94e6668
commit 2c42257314
2 changed files with 30 additions and 12 deletions
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14
elf/dl-open.c
View File

@ -844,15 +844,13 @@ _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);
GL(dl_ns)[nsid].libc_map = NULL;
_dl_debug_update (nsid)->r_state = RT_CONSISTENT;
}
/* Never allow loading a DSO in a namespace which is empty. Such

28
elf/tst-dlmopen-twice.c
View File

@ -16,18 +16,38 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <support/xdlfcn.h>
#include <stdio.h>
#include <support/check.h>
#include <support/xdlfcn.h>
static int
do_test (void)
/* Run the test multiple times, to check finding a new namespace while
another namespace is already in use. This used to trigger bug 29600. */
static void
recurse (int depth)
{
void *handle = xdlmopen (LM_ID_NEWLM, "tst-dlmopen-twice-mod1.so", RTLD_NOW);
if (depth == 0)
return;
printf ("info: running at depth %d\n", depth);
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);
recurse (depth - 1);
xdlclose (handle);
}
static int
do_test (void)
{
/* First run the test without nesting. */
recurse (1);
/* Then with nesting. The constant needs to be less than the
internal DL_NNS namespace constant. */
recurse (10);
return 0;
}