[LTP] [PATCH] hugeshmctl02: Skipped EFAULT tests for libc variant

[Li Wang]

On Thu, Jun 15, 2023 at 5:40 PM Dylan Jhong <dylan@andestech.com> wrote:

> When testing hugeshmctl02 under the 32bit architecture, a segmentation
> fault
> will occur. This patch will skip EFAULT tests for libc variant.
>
> Hugeshmctl02 will intentionally pass "(struct shmid_ds *)-1" to shmctl(),
> but
> glibc will perform an additional conversion function when the architecture
> is
> 32bit, which will try to copy all items in (struct shmid_ds *) to another
> structure[*1]. In the process of copying, it is necessary to dereference
> "(struct shmid_ds *)-1", resulting in segmentation fault.
>
> The LTP also has similar problems before, this patch is reference from the
> shmctl03 patch[*2].
>
> [*1]:
> https://github.com/bminor/glibc/blob/master/sysdeps/unix/sysv/linux/shmctl.c#L37
> [*2]:
> https://github.com/linux-test-project/ltp/commit/a5a80aa8485a7cb017f96aba8d7b5ea79f1ba4d4
>
> Signed-off-by: Dylan Jhong <dylan@andestech.com>
> ---
>  .../mem/hugetlb/hugeshmctl/hugeshmctl02.c     | 35 ++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl02.c
> b/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl02.c
> index 0bc9ffd74..e9c2e9fc8 100644
> --- a/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl02.c
> +++ b/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl02.c
> @@ -27,6 +27,7 @@
>  #include <pwd.h>
>  #include <limits.h>
>  #include "hugetlb.h"
> +#include "lapi/syscalls.h"
>
>  static size_t shm_size;
>  static int shm_id_1 = -1;
> @@ -50,9 +51,37 @@ struct tcase {
>         {&shm_id_2, -1, &buf, EINVAL},
>  };
>
> +static int libc_shmctl(int shmid, int cmd, void *buf)
> +{
> +       return shmctl(shmid, cmd, buf);
> +}
> +
> +static int sys_shmctl(int shmid, int cmd, void *buf)
> +{
> +       return tst_syscall(__NR_shmctl, shmid, cmd, buf);
> +}
> +
> +static struct test_variants
> +{
> +       int (*shmctl)(int shmid, int cmd, void *buf);
> +       char *desc;
> +} variants[] = {
> +       { .shmctl = libc_shmctl, .desc = "libc shmctl()"},
> +#if (__NR_shmctl != __LTP__NR_INVALID_SYSCALL)
> +       { .shmctl = sys_shmctl,  .desc = "__NR_shmctl syscall"},
> +#endif
> +};
> +
>  static void test_hugeshmctl(unsigned int i)
>  {
> -       TEST(shmctl(*(tcases[i].shmid), tcases[i].cmd, tcases[i].sbuf));
> +       struct test_variants *tv = &variants[tst_variant];
> +
> +       if (tcases[i].error == EFAULT && tv->shmctl == libc_shmctl) {
>

You pointed the segment fault only exists on 32bit when use
libc wrapper, but this condition skips for both 64and32 bits,
isn't it?

I guess the strict condition should be as below?

    if (tcases[i].error == EFAULT && tv->shmctl == libc_shmctl &&
tst_kernel_bits() == 32) {
    ...
    }



> +               tst_res(TCONF, "EFAULT is skipped for libc variant");
> +               return;
> +       }
> +
> +       TEST(tv->shmctl(*(tcases[i].shmid), tcases[i].cmd,
> tcases[i].sbuf));
>         if (TST_RET != -1) {
>                 tst_res(TFAIL, "shmctl succeeded unexpectedly");
>                 return;
> @@ -70,8 +99,11 @@ static void test_hugeshmctl(unsigned int i)
>
>  static void setup(void)
>  {
> +       struct test_variants *tv = &variants[tst_variant];
>         long hpage_size;
>
> +       tst_res(TINFO, "Testing variant: %s", tv->desc);
> +
>         if (tst_hugepages == 0)
>                 tst_brk(TCONF, "No enough hugepages for testing.");
>
> @@ -101,6 +133,7 @@ static void cleanup(void)
>
>  static struct tst_test test = {
>         .test = test_hugeshmctl,
> +       .test_variants = ARRAY_SIZE(variants),
>         .tcnt = ARRAY_SIZE(tcases),
>         .needs_root = 1,
>         .needs_tmpdir = 1,
> --
> 2.34.1
>
>
> --
> Mailing list info: https://lists.linux.it/listinfo/ltp
>
>

-- 
Regards,
Li Wang