[PATCH 08/19] nptl: Use __pthread_attr_copy in pthread_getattr_default_np (bug 25999)
Carlos O'Donell
carlos@redhat.com
Wed May 20 14:42:56 GMT 2020
On 5/19/20 6:44 AM, Florian Weimer via Libc-alpha wrote:
> pthread_getattr_default_np needs to make a deep copy.
Agreed, this seems like an oversight regarding the affinity.
I expect not enough programs ever use the kind of setup you run in
the test, but it's still wrong, we should be doing a deep copy.
Tested clean on x86_64 and i686.
OK for master.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
> ---
> nptl/Makefile | 1 +
> nptl/pthread_getattr_default_np.c | 12 ++---
> nptl/tst-pthread-defaultattr-free.c | 78 +++++++++++++++++++++++++++++
> 3 files changed, 82 insertions(+), 9 deletions(-)
> create mode 100644 nptl/tst-pthread-defaultattr-free.c
>
> diff --git a/nptl/Makefile b/nptl/Makefile
> index b4aaad0f20..e5686b20ac 100644
> --- a/nptl/Makefile
> +++ b/nptl/Makefile
> @@ -328,6 +328,7 @@ tests = tst-attr2 tst-attr3 tst-default-attr \
> tst-thread-affinity-pthread \
> tst-thread-affinity-pthread2 \
> tst-thread-affinity-sched \
> + tst-pthread-defaultattr-free \
OK.
>
>
> tests-container = tst-pthread-getattr
> diff --git a/nptl/pthread_getattr_default_np.c b/nptl/pthread_getattr_default_np.c
> index cce20cbe94..a9665c5df7 100644
> --- a/nptl/pthread_getattr_default_np.c
> +++ b/nptl/pthread_getattr_default_np.c
> @@ -16,20 +16,14 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> -#include <errno.h>
> -#include <stdlib.h>
> #include <pthreadP.h>
>
> int
> pthread_getattr_default_np (pthread_attr_t *out)
> {
> - struct pthread_attr *real_out;
> -
> - real_out = (struct pthread_attr *) out;
> -
> lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
> - *real_out = __default_pthread_attr;
> + int ret = __pthread_attr_copy (out,
> + (pthread_attr_t *) &__default_pthread_attr);
OK. Locks kept in place, and call to __pthread_attr_copy owns the struct.
> lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
> -
> - return 0;
> + return ret;
> }
> diff --git a/nptl/tst-pthread-defaultattr-free.c b/nptl/tst-pthread-defaultattr-free.c
> new file mode 100644
> index 0000000000..5a84302380
> --- /dev/null
> +++ b/nptl/tst-pthread-defaultattr-free.c
> @@ -0,0 +1,78 @@
> +/* Test for user-after-free bug in pthread_getattr_default_np (bug 25999).
OK.
> + Copyright (C) 2020 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 <pthread.h>
> +#include <sched.h>
> +#include <support/check.h>
> +#include <support/xthread.h>
> +
> +static int
> +do_test (void)
> +{
> + /* This is a typical affinity size. */
> + enum { cpu_count = 128 };
> + cpu_set_t *set = CPU_ALLOC (cpu_count);
> + size_t set_size = CPU_ALLOC_SIZE (cpu_count);
> + CPU_ZERO_S (set_size, set);
> + CPU_SET (1, set);
> + CPU_SET (3, set);
OK.
> +
> + /* Apply the affinity mask to the default attribute. */
> + pthread_attr_t attr;
> + xpthread_attr_init (&attr);
> + TEST_COMPARE (pthread_attr_setaffinity_np (&attr, set_size, set), 0);
> + TEST_COMPARE (pthread_setattr_default_np (&attr), 0);
OK. Set the default.
> + xpthread_attr_destroy (&attr);
OK.
> +
> + /* Read back the default attribute and check affinity mask. */
> + pthread_getattr_default_np (&attr);
> + CPU_ZERO_S (set_size, set);
> + TEST_COMPARE (pthread_attr_getaffinity_np (&attr, set_size, set), 0);
> + for (int i = 0; i < cpu_count; ++i)
> + TEST_COMPARE (!!CPU_ISSET (i, set), i == 1 || i == 3);
OK.
> +
> +
> + /* Apply a larger CPU affinity mask to the default attribute, to
> + trigger reallocation. */
> + {
> + cpu_set_t *large_set = CPU_ALLOC (4 * cpu_count);
> + size_t large_set_size = CPU_ALLOC_SIZE (4 * cpu_count);
> + CPU_ZERO_S (large_set_size, large_set);
> + pthread_attr_t large_attr;
> + xpthread_attr_init (&large_attr);
> + TEST_COMPARE (pthread_attr_setaffinity_np (&large_attr,
> + large_set_size, large_set), 0);
> + TEST_COMPARE (pthread_setattr_default_np (&large_attr), 0);
OK.
> + xpthread_attr_destroy (&large_attr);
> + CPU_FREE (large_set);
> + }
> +
> + /* Read back the default attribute and check affinity mask. */
> + CPU_ZERO_S (set_size, set);
> + TEST_COMPARE (pthread_attr_getaffinity_np (&attr, set_size, set), 0);
> + for (int i = 0; i < cpu_count; ++i)
> + TEST_COMPARE (!!CPU_ISSET (i, set), i == 1 || i == 3);
> + /* Due to bug 25999, the following caused a double-free abort. */
> + xpthread_attr_destroy (&attr);
OK.
> +
> + CPU_FREE (set);
> +
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
>
--
Cheers,
Carlos.
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