Hi!
> commit: ce436509a8e109330c56bb4d8ec87d258788f5f4 ("[PATCH v4 2/3] fs: openat2: Extend open_how to allow userspace-selected fds")
> url: https://github.com/0day-ci/linux/commits/Josh-Triplett/Support-userspace-selected-fds/20200414-102939
> base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next
This commit adds fd parameter to the how structure where LTP test was
previously passing garbage, which obviously causes the difference in
errno.
This could be safely ignored for now, if the patch gets merged the test
needs to be updated.
--
[email protected]
On 2020-04-27, Cyril Hrubis <[email protected]> wrote:
> Hi!
> > commit: ce436509a8e109330c56bb4d8ec87d258788f5f4 ("[PATCH v4 2/3] fs: openat2: Extend open_how to allow userspace-selected fds")
> > url: https://github.com/0day-ci/linux/commits/Josh-Triplett/Support-userspace-selected-fds/20200414-102939
> > base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next
>
> This commit adds fd parameter to the how structure where LTP test was
> previously passing garbage, which obviously causes the difference in
> errno.
>
> This could be safely ignored for now, if the patch gets merged the test
> needs to be updated.
It wouldn't be a bad idea to switch the test to figure out the ksize of
the struct, so that you only add bad padding after that. But then again,
this would be a bit ugly -- having CHECK_FIELDS would make this simpler.
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
Hi!
> > > commit: ce436509a8e109330c56bb4d8ec87d258788f5f4 ("[PATCH v4 2/3] fs: openat2: Extend open_how to allow userspace-selected fds")
> > > url: https://github.com/0day-ci/linux/commits/Josh-Triplett/Support-userspace-selected-fds/20200414-102939
> > > base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next
> >
> > This commit adds fd parameter to the how structure where LTP test was
> > previously passing garbage, which obviously causes the difference in
> > errno.
> >
> > This could be safely ignored for now, if the patch gets merged the test
> > needs to be updated.
>
> It wouldn't be a bad idea to switch the test to figure out the ksize of
> the struct, so that you only add bad padding after that. But then again,
> this would be a bit ugly -- having CHECK_FIELDS would make this simpler.
Any pointers how can be the size figured out without relying on the
E2BIG we are testing for? Does the kernel export it somewhere?
--
Cyril Hrubis
[email protected]
On 2020-04-28, Cyril Hrubis <[email protected]> wrote:
> Hi!
> > > > commit: ce436509a8e109330c56bb4d8ec87d258788f5f4 ("[PATCH v4 2/3] fs: openat2: Extend open_how to allow userspace-selected fds")
> > > > url: https://github.com/0day-ci/linux/commits/Josh-Triplett/Support-userspace-selected-fds/20200414-102939
> > > > base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next
> > >
> > > This commit adds fd parameter to the how structure where LTP test was
> > > previously passing garbage, which obviously causes the difference in
> > > errno.
> > >
> > > This could be safely ignored for now, if the patch gets merged the test
> > > needs to be updated.
> >
> > It wouldn't be a bad idea to switch the test to figure out the ksize of
> > the struct, so that you only add bad padding after that. But then again,
> > this would be a bit ugly -- having CHECK_FIELDS would make this simpler.
>
> Any pointers how can be the size figured out without relying on the
> E2BIG we are testing for? Does the kernel export it somewhere?
No, you would have to effectively binary search on -E2BIG at the moment.
CHECK_FIELDS is a proposal I have which would allow you to get get the
size of the in-kernel struct, but it's still a proposal.
In theory you could get the size through BTF, but it's probably more
effort than it's worth to implement that.
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>