On Mon, Mar 04, 2024 at 08:27:50PM +0100, Mickaël Salaün wrote:
> Testing the whole series, I found that some Landlock tests are flaky
> starting with this patch. I tried to not use the longjmp in the
> grandchild but it didn't change. I suspect missing volatiles but I
> didn't find the faulty one(s) yet. :/
> I'll continue investigating tomorrow but help would be much appreciated!
The issue is with the fs_test.c, often starting with this one:
# RUN layout1.relative_chroot_only ...
# fs_test.c:294:relative_chroot_only:Expected 0 (0) == umount(TMP_DIR) (-1)
# fs_test.c:296:relative_chroot_only:Expected 0 (0) == remove_path(TMP_DIR) (16)
# relative_chroot_only: Test failed
# FAIL layout1.relative_chroot_only
...or this one:
# RUN layout3_fs.hostfs.tag_inode_dir_child ...
# fs_test.c:4707:tag_inode_dir_child:Expected 0 (0) == mkdir(self->dir_path, 0700) (-1)
# fs_test.c:4709:tag_inode_dir_child:Failed to create directory "tmp/dir": No such file or directory
# fs_test.c:4724:tag_inode_dir_child:Expected 0 (0) <= fd (-1)
# fs_test.c:4726:tag_inode_dir_child:Failed to create file "tmp/dir/file": No such file or directory
# fs_test.c:4729:tag_inode_dir_child:Expected 0 (0) == close(fd) (-1)
# tag_inode_dir_child: Test failed
# FAIL layout3_fs.hostfs.tag_inode_dir_child
>
>
> On Wed, Feb 28, 2024 at 04:59:09PM -0800, Jakub Kicinski wrote:
> > From: Mickaël Salaün <mic@xxxxxxxxxxx>
> >
> > Replace Landlock-specific TEST_F_FORK() with an improved TEST_F() which
> > brings four related changes:
> >
> > Run TEST_F()'s tests in a grandchild process to make it possible to
> > drop privileges and delegate teardown to the parent.
> >
> > Compared to TEST_F_FORK(), simplify handling of the test grandchild
> > process thanks to vfork(2), and makes it generic (e.g. no explicit
> > conversion between exit code and _metadata).
> >
> > Compared to TEST_F_FORK(), run teardown even when tests failed with an
> > assert thanks to commit 63e6b2a42342 ("selftests/harness: Run TEARDOWN
> > for ASSERT failures").
> >
> > Simplify the test harness code by removing the no_print and step fields
> > which are not used. I added this feature just after I made
> > kselftest_harness.h more broadly available but this step counter
> > remained even though it wasn't needed after all. See commit 369130b63178
> > ("selftests: Enhance kselftest_harness.h to print which assert failed").
> >
> > Replace spaces with tabs in one line of __TEST_F_IMPL().
> >
> > Cc: Günther Noack <gnoack@xxxxxxxxxx>
> > Cc: Shuah Khan <shuah@xxxxxxxxxx>
> > Cc: Will Drewry <wad@xxxxxxxxxxxx>
> > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx>
> > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> > Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
> > --
> > v4:
> > - GAND -> GRAND
> > - init child to 1, otherwise assert in setup triggers a longjmp
> > which in turn reads child without it ever getting initialized
> > (or being 0, i.e. we mistakenly assume we're in the grandchild)
>
> Good catch!
