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H A D | userfaultfd.c | diff 2ff559f31a5d50c31a3f9d849f8af90dc36c7105 Wed Apr 12 11:38:52 CDT 2023 Peter Xu <peterx@redhat.com> Revert "userfaultfd: don't fail on unrecognized features"
This is a proposal to revert commit 914eedcb9ba0ff53c33808.
I found this when writing a simple UFFDIO_API test to be the first unit test in this set. Two things breaks with the commit:
- UFFDIO_API check was lost and missing. According to man page, the kernel should reject ioctl(UFFDIO_API) if uffdio_api.api != 0xaa. This check is needed if the api version will be extended in the future, or user app won't be able to identify which is a new kernel.
- Feature flags checks were removed, which means UFFDIO_API with a feature that does not exist will also succeed. According to the man page, we should (and it makes sense) to reject ioctl(UFFDIO_API) if unknown features passed in.
Link: https://lore.kernel.org/r/20220722201513.1624158-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20230412163922.327282-2-peterx@redhat.com Fixes: 914eedcb9ba0 ("userfaultfd: don't fail on unrecognized features") Signed-off-by: Peter Xu <peterx@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Zach O'Keefe <zokeefe@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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