[LTP] [PATCH 1/1] recvmmsg01: Workaround segfault on libc variant on 32 bit

[Wei Gao]

On Fri, Nov 08, 2024 at 01:21:39PM +0100, Petr Vorel wrote:
> EFAULT test segfaults on newer kernels (e.g. 6.4) on libc variant on
> 32bit.  Use typical LTP workaround to test by forked child + checking
> the terminating signal.
> 
> NOTE: testing kernel variants could be done without forking child, but
> use it as well for simplicity.
> 
> Suggested-by: Cyril Hrubis <chrubis@suse.cz>
> Signed-off-by: Petr Vorel <pvorel@suse.cz>
> ---
> NOTE: working on other 3 tests affected by the same problem
> (mq_timedreceive01.c, mq_timedsend01.c,  sigtimedwait01.c).
> 
>  .../kernel/syscalls/recvmmsg/recvmmsg01.c     | 48 +++++++++++++++----
>  1 file changed, 40 insertions(+), 8 deletions(-)
> 
> diff --git a/testcases/kernel/syscalls/recvmmsg/recvmmsg01.c b/testcases/kernel/syscalls/recvmmsg/recvmmsg01.c
> index fb21ea1e70..46658b133d 100644
> --- a/testcases/kernel/syscalls/recvmmsg/recvmmsg01.c
> +++ b/testcases/kernel/syscalls/recvmmsg/recvmmsg01.c
> @@ -47,7 +47,7 @@ static struct test_case tcase[] = {
>  		.desc = "bad message vector address",
>  		.fd = &receive_sockfd,
>  		.exp_errno = EFAULT,
> -		.msg_vec = (void*)&bad_addr,
> +		.msg_vec = (void *)&bad_addr,
>  	},
>  	{
>  		.desc = "negative seconds in timeout",
> @@ -74,23 +74,54 @@ static struct test_case tcase[] = {
>  	}
>  };
>  
> -static void do_test(unsigned int i)
> +static void verify_recvmmsg(unsigned int i, void *timeout)
>  {
>  	struct time64_variants *tv = &variants[tst_variant];
>  	struct test_case *tc = &tcase[i];
> -	void *timeout;
>  
>  	ts.type = tv->ts_type;
>  	tst_ts_set_sec(&ts, tc->tv_sec);
>  	tst_ts_set_nsec(&ts, tc->tv_nsec);
>  
> +	TST_EXP_FAIL2(tv->recvmmsg(*tc->fd, *tc->msg_vec, VLEN, 0, timeout),
> +		      tc->exp_errno, "recvmmsg() %s", tc->desc);
> +}
> +
> +static void test_bad_addr(unsigned int i)
> +{
> +	struct time64_variants *tv = &variants[tst_variant];
> +	void *timeout = bad_addr;
> +	pid_t pid;
> +	int status;
> +
> +	pid = SAFE_FORK();
> +	if (!pid) {
> +		verify_recvmmsg(i, timeout);
> +		_exit(!TST_PASS);
> +	}
> +
> +	SAFE_WAITPID(pid, &status, 0);
> +
> +	if (WIFEXITED(status))
> +		return;
> +
> +	if (tv->ts_type == TST_LIBC_TIMESPEC &&
> +		WIFSIGNALED(status) && WTERMSIG(status) == SIGSEGV) {
> +		tst_res(TPASS, "Child killed by signal");
very nit: 
1) s/Child killed by signal/Child killed by SIGSEGV signal/
2) suggest also print out tc->desc

Thanks for create patch fix our current issue.
Reviewed-by: Wei Gao <wegao@suse.com>
> +		return;
> +	}
> +
> +	tst_res(TFAIL, "Child %s", tst_strstatus(status));
> +}
> +
> +static void do_test(unsigned int i)
> +{
> +	struct test_case *tc = &tcase[i];
> +
>  	if (tc->bad_ts_addr)
> -		timeout = bad_addr;
> +		test_bad_addr(i);
>  	else
> -		timeout = tst_ts_get(&ts);
> -
> -	TST_EXP_FAIL2(tv->recvmmsg(*tc->fd, *tc->msg_vec, VLEN, 0, timeout),
> -	             tc->exp_errno, "recvmmsg() %s", tc->desc);
> +		verify_recvmmsg(i, tst_ts_get(&ts));
>  }
>  
>  static void setup(void)
> @@ -139,6 +170,7 @@ static struct tst_test test = {
>  	.setup = setup,
>  	.cleanup = cleanup,
>  	.test_variants = ARRAY_SIZE(variants),
> +	.forks_child = 1,
>  	.bufs = (struct tst_buffers []) {
>  		{&iov, .iov_sizes = (int[]){1, -1}},
>  		{&msg, .size = VLEN * sizeof(*msg)},
> -- 
> 2.45.2
>