The `pselect_fd_too_big` test is checking for the case where the `nfds` is larger than the number of open files allowed for this process (RLIMIT_NOFILE). According to the man page, if `nfds` > RLIMIT_NOFILE is evaluate to true the pselect6 syscall should return EINVAL.
In fact, the Linux implementation of the pselect6 syscall[1] does not compare the `nfds` and RLIMIT_NOFILE but rather caps `nfds` to the highest numbered fd of the current process. It was observed elsewhere that there is a discrepancy between the manual page and the implementation [2]. As a solution, replace the current testcase with one that checks the behaviour of the syscall when passed an invalid FD. [1]:https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/select.c#n619 [2]:https://patchwork.kernel.org/patch/9345805/ Signed-off-by: Francis Deslauriers <francis.deslauri...@efficios.com> Signed-off-by: Julien Desfossez <jdesfos...@efficios.com> --- tests/regression/kernel/select_poll_epoll.c | 39 +++++++++++++--------- tests/regression/kernel/test_select_poll_epoll | 6 ++-- .../kernel/validate_select_poll_epoll.py | 13 ++++---- 3 files changed, 33 insertions(+), 25 deletions(-) diff --git a/tests/regression/kernel/select_poll_epoll.c b/tests/regression/kernel/select_poll_epoll.c index 4b703b3..1d767b0 100644 --- a/tests/regression/kernel/select_poll_epoll.c +++ b/tests/regression/kernel/select_poll_epoll.c @@ -437,30 +437,38 @@ void ppoll_fds_ulong_max(void) } /* - * Select is limited to 1024 FDs, should output a pselect event - * with 0 FDs. + * Pass a invalid file descriptor to pselect6(). The syscall should return + * -EBADF. The recorded event should contain a ret=-EBADF (-9). */ -void pselect_fd_too_big(void) +void pselect_invalid_fd(void) { - long rfds[2048 / (sizeof(long) * CHAR_BIT)] = { 0 }; + fd_set rfds; int ret; - int fd2; + int fd; char buf[BUF_SIZE]; /* - * Test if nfds > 1024. - * Make sure ulimit is set correctly (ulimit -n 2048). + * Open a file, close it and use the closed FD in the pselect6 call */ - fd2 = dup2(wait_fd, 2047); - if (fd2 != 2047) { - perror("dup2"); - return; + + fd = open("/dev/null", O_RDONLY); + if (fd == -1) { + perror("open"); + goto error; } - FD_SET(fd2, (fd_set *) &rfds); - ret = syscall(SYS_pselect6, fd2 + 1, &rfds, NULL, NULL, NULL, NULL); + ret = close(fd); if (ret == -1) { + perror("close"); + goto error; + } + + FD_ZERO(&rfds); + FD_SET(fd, &rfds); + + ret = syscall(SYS_pselect6, fd + 1, &rfds, NULL, NULL, NULL, NULL); + if (ret == -1) { perror("# pselect()"); } else if (ret) { printf("# [pselect] data available\n"); @@ -471,7 +479,8 @@ void pselect_fd_too_big(void) } else { printf("# [pselect] timeout\n"); } - +error: + return; } /* @@ -892,7 +901,7 @@ int main(int argc, const char **argv) run_working_cases(); break; case 3: - pselect_fd_too_big(); + pselect_invalid_fd(); break; case 4: test_ppoll_big(); diff --git a/tests/regression/kernel/test_select_poll_epoll b/tests/regression/kernel/test_select_poll_epoll index e01866f..ec034e6 100755 --- a/tests/regression/kernel/test_select_poll_epoll +++ b/tests/regression/kernel/test_select_poll_epoll @@ -126,13 +126,13 @@ function test_timeout_cases() rm -rf $TRACE_PATH } -function test_big_pselect() +function test_pselect_invalid_fd() { TRACE_PATH=$(mktemp -d) SESSION_NAME="syscall_payload" SYSCALL_LIST="pselect6" - diag "pselect with a FD > 1023" + diag "pselect with invalid FD" create_lttng_session_ok $SESSION_NAME $TRACE_PATH @@ -384,7 +384,7 @@ skip $isroot "Root access is needed. Skipping all tests." $NUM_TESTS || test_working_cases test_timeout_cases - test_big_pselect + test_pselect_invalid_fd test_big_ppoll test_ppoll_overflow test_pselect_invalid_ptr diff --git a/tests/regression/kernel/validate_select_poll_epoll.py b/tests/regression/kernel/validate_select_poll_epoll.py index f4946e7..613cec3 100755 --- a/tests/regression/kernel/validate_select_poll_epoll.py +++ b/tests/regression/kernel/validate_select_poll_epoll.py @@ -450,8 +450,8 @@ class Test2(TraceParser): class Test3(TraceParser): def __init__(self, trace, pid): super().__init__(trace, pid) - self.expect["select_too_big_in"] = 0 - self.expect["select_too_big_out"] = 0 + self.expect["select_invalid_fd_in"] = 0 + self.expect["select_invalid_fd_out"] = 0 def select_entry(self, event): timestamp = event.timestamp @@ -466,9 +466,8 @@ class Test3(TraceParser): _exceptfds_length = event["_exceptfds_length"] exceptfds = event["exceptfds"] - # make sure an invalid value still produces a valid event - if n == 2048 and overflow == 0 and _readfds_length == 0: - self.expect["select_too_big_in"] = 1 + if n > 0 and overflow == 0: + self.expect["select_invalid_fd_in"] = 1 def select_exit(self, event): timestamp = event.timestamp @@ -483,9 +482,9 @@ class Test3(TraceParser): _exceptfds_length = event["_exceptfds_length"] exceptfds = event["exceptfds"] - # make sure an invalid value still produces a valid event + # make sure the event has a ret field equal to -EBADF if ret == -9 and overflow == 0 and _readfds_length == 0: - self.expect["select_too_big_out"] = 1 + self.expect["select_invalid_fd_out"] = 1 class Test4(TraceParser): -- 2.7.4 _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
