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elf: Add all malloc tunable to unsecvars
Some environment variables allow alteration of allocator behavior across setuid boundaries, where a setuid program may ignore the tunable, but its non-setuid child can read it and adjust the memory allocator behavior accordingly. Most library behavior tunings is limited to the current process and does not bleed in scope; so it is unclear how pratical this misfeature is. If behavior change across privilege boundaries is desirable, it would be better done with a wrapper program around the non-setuid child that sets these envvars, instead of using the setuid process as the messenger. The patch as fixes tst-env-setuid, where it fail if any unsecvars is set. It also adds a dynamic test, although it requires --enable-hardcoded-path-in-tests so kernel correctly sets the setuid bit (using the loader command directly would require to set the setuid bit on the loader itself, which is not a usual deployment). Co-authored-by: Siddhesh Poyarekar <siddhesh@sourceware.org> Checked on x86_64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Adhemerval Zanella
parent
9c96c87d60
commit
11f7e3dd8f
@ -262,7 +262,7 @@ tests-static-normal := \
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tst-array5-static \
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tst-dl-iter-static \
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tst-dst-static \
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tst-env-setuid \
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tst-env-setuid-static \
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tst-getauxval-static \
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tst-linkall-static \
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tst-single_threaded-pthread-static \
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@ -306,6 +306,7 @@ tests := \
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tst-auxv \
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tst-decorate-maps \
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tst-dl-hash \
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tst-env-setuid \
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tst-leaks1 \
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tst-stringtable \
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tst-tls9 \
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@ -2433,9 +2434,6 @@ $(objpfx)tst-nodelete-dlclose: $(objpfx)tst-nodelete-dlclose-dso.so
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$(objpfx)tst-nodelete-dlclose.out: $(objpfx)tst-nodelete-dlclose-dso.so \
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$(objpfx)tst-nodelete-dlclose-plugin.so
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tst-env-setuid-ENV = MALLOC_CHECK_=2 MALLOC_MMAP_THRESHOLD_=4096 \
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LD_HWCAP_MASK=0x1
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$(objpfx)tst-debug1.out: $(objpfx)tst-debug1mod1.so
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$(objpfx)tst-debug1mod1.so: $(objpfx)testobj1.so
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@ -3002,3 +3000,5 @@ $(objpfx)tst-non-directory-path.out: tst-non-directory-path.sh \
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'$(test-wrapper-env)' '$(run_program_env)' \
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'$(rpath-link)' $(objpfx) > $@; \
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$(evaluate-test)
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tst-env-setuid-ARGS = -- $(host-test-program-cmd)
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1
elf/tst-env-setuid-static.c
Normal file
1
elf/tst-env-setuid-static.c
Normal file
@ -0,0 +1 @@
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#include "tst-env-setuid.c"
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@ -15,18 +15,14 @@
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Verify that tunables correctly filter out unsafe environment variables like
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MALLOC_CHECK_ and MALLOC_MMAP_THRESHOLD_ but also retain
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MALLOC_MMAP_THRESHOLD_ in an unprivileged child. */
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/* Verify that correctly filter out unsafe environment variables defined
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in unsecvars.h. */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <array_length.h>
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#include <gnu/lib-names.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <support/check.h>
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@ -36,61 +32,72 @@
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static char SETGID_CHILD[] = "setgid-child";
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#ifndef test_child
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#define FILTERED_VALUE "some-filtered-value"
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#define UNFILTERED_VALUE "some-unfiltered-value"
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struct envvar_t
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{
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const char *env;
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const char *value;
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};
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/* That is not an extensible list of all filtered out environment
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variables. */
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static const struct envvar_t filtered_envvars[] =
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{
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{ "GLIBC_TUNABLES", FILTERED_VALUE },
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{ "LD_AUDIT", FILTERED_VALUE },
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{ "LD_HWCAP_MASK", FILTERED_VALUE },
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{ "LD_LIBRARY_PATH", FILTERED_VALUE },
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{ "LD_PRELOAD", FILTERED_VALUE },
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{ "LD_PROFILE", FILTERED_VALUE },
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{ "MALLOC_ARENA_MAX", FILTERED_VALUE },
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{ "MALLOC_PERTURB_", FILTERED_VALUE },
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{ "MALLOC_TRACE", FILTERED_VALUE },
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{ "MALLOC_TRIM_THRESHOLD_", FILTERED_VALUE },
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{ "RES_OPTIONS", FILTERED_VALUE },
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};
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static const struct envvar_t unfiltered_envvars[] =
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{
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{ "LD_BIND_NOW", "0" },
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{ "LD_BIND_NOT", "1" },
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/* Non longer supported option. */
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{ "LD_ASSUME_KERNEL", UNFILTERED_VALUE },
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};
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static int
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test_child (void)
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{
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if (getenv ("MALLOC_CHECK_") != NULL)
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int ret = 0;
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for (const struct envvar_t *e = filtered_envvars;
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e != array_end (filtered_envvars);
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e++)
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{
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printf ("MALLOC_CHECK_ is still set\n");
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return 1;
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const char *env = getenv (e->env);
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ret |= env != NULL;
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}
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if (getenv ("MALLOC_MMAP_THRESHOLD_") == NULL)
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for (const struct envvar_t *e = unfiltered_envvars;
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e != array_end (unfiltered_envvars);
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e++)
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{
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printf ("MALLOC_MMAP_THRESHOLD_ lost\n");
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return 1;
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const char *env = getenv (e->env);
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ret |= !(env != NULL && strcmp (env, e->value) == 0);
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}
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if (getenv ("LD_HWCAP_MASK") != NULL)
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{
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printf ("LD_HWCAP_MASK still set\n");
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return 1;
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}
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return 0;
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return ret;
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}
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#endif
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#ifndef test_parent
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static int
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test_parent (void)
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{
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if (getenv ("MALLOC_CHECK_") == NULL)
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{
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printf ("MALLOC_CHECK_ lost\n");
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return 1;
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}
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if (getenv ("MALLOC_MMAP_THRESHOLD_") == NULL)
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{
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printf ("MALLOC_MMAP_THRESHOLD_ lost\n");
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return 1;
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}
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if (getenv ("LD_HWCAP_MASK") == NULL)
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{
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printf ("LD_HWCAP_MASK lost\n");
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return 1;
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}
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return 0;
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}
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#endif
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static int
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do_test (int argc, char **argv)
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{
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/* For dynamic loader, the test requires --enable-hardcoded-path-in-tests so
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the kernel sets the AT_SECURE on process initialization. */
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if (argc >= 2 && strstr (argv[1], LD_SO) != 0)
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FAIL_UNSUPPORTED ("dynamic test requires --enable-hardcoded-path-in-tests");
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/* Setgid child process. */
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if (argc == 2 && strcmp (argv[1], SETGID_CHILD) == 0)
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{
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@ -104,20 +111,33 @@ do_test (int argc, char **argv)
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if (ret != 0)
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exit (1);
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exit (EXIT_SUCCESS);
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/* Special return code to make sure that the child executed all the way
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through. */
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exit (42);
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}
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else
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{
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if (test_parent () != 0)
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exit (1);
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for (const struct envvar_t *e = filtered_envvars;
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e != array_end (filtered_envvars);
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e++)
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setenv (e->env, e->value, 1);
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for (const struct envvar_t *e = unfiltered_envvars;
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e != array_end (unfiltered_envvars);
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e++)
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setenv (e->env, e->value, 1);
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int status = support_capture_subprogram_self_sgid (SETGID_CHILD);
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if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
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return EXIT_UNSUPPORTED;
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exit (EXIT_UNSUPPORTED);
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if (!WIFEXITED (status))
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FAIL_EXIT1 ("Unexpected exit status %d from child process\n", status);
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if (WEXITSTATUS (status) != 42)
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{
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printf (" child failed with status %d\n",
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WEXITSTATUS (status));
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support_record_failure ();
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}
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return 0;
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}
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@ -18,7 +18,14 @@
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"LD_SHOW_AUXV\0" \
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"LOCALDOMAIN\0" \
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"LOCPATH\0" \
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"MALLOC_ARENA_MAX\0" \
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"MALLOC_ARENA_TEST\0" \
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"MALLOC_MMAP_MAX_\0" \
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"MALLOC_MMAP_THRESHOLD_\0" \
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"MALLOC_PERTURB_\0" \
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"MALLOC_TOP_PAD_\0" \
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"MALLOC_TRACE\0" \
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"MALLOC_TRIM_THRESHOLD_\0" \
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"NIS_PATH\0" \
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"NLSPATH\0" \
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"RESOLV_HOST_CONF\0" \
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