[PATCH v2] elf: Call __libc_early_init for reused namespaces (bug 29528)
H.J. Lu
hjl.tools@gmail.com
Fri Aug 26 18:29:46 GMT 2022
On Fri, Aug 26, 2022 at 11:10 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> 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.
>
> ---
> v2: Fix C&P error in trace message.
> elf/Makefile | 7 +++++++
> elf/dl-open.c | 13 +++++++-----
> elf/tst-dlmopen-twice-mod1.c | 37 ++++++++++++++++++++++++++++++++
> elf/tst-dlmopen-twice-mod2.c | 50 ++++++++++++++++++++++++++++++++++++++++++++
> elf/tst-dlmopen-twice.c | 34 ++++++++++++++++++++++++++++++
> 5 files changed, 136 insertions(+), 5 deletions(-)
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 3928a08787..008770bfaf 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -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
> diff --git a/elf/dl-open.c b/elf/dl-open.c
> index a23e65926b..46e8066fd8 100644
> --- a/elf/dl-open.c
> +++ b/elf/dl-open.c
> @@ -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;
> }
> diff --git a/elf/tst-dlmopen-twice-mod1.c b/elf/tst-dlmopen-twice-mod1.c
> new file mode 100644
> index 0000000000..0eaf04948c
> --- /dev/null
> +++ b/elf/tst-dlmopen-twice-mod1.c
> @@ -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];
> diff --git a/elf/tst-dlmopen-twice-mod2.c b/elf/tst-dlmopen-twice-mod2.c
> new file mode 100644
> index 0000000000..40c6c01f96
> --- /dev/null
> +++ b/elf/tst-dlmopen-twice-mod2.c
> @@ -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;
> +}
> diff --git a/elf/tst-dlmopen-twice.c b/elf/tst-dlmopen-twice.c
> new file mode 100644
> index 0000000000..449f3c8fa9
> --- /dev/null
> +++ b/elf/tst-dlmopen-twice.c
> @@ -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>
>
> base-commit: 5ecc98241229d494aaad23a4a3fe106fe11e1f40
>
LGTM.
Thanks.
--
H.J.
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