selftests/mm: fix ptrace PEEKDATA check in memfd_secret test

try_ptrace() treats PTRACE_PEEKDATA return value as a boolean check.  A
successful read returns non-zero data (memory filled with 0x55), causing
the test to incorrectly report PASS when secret memory protection is
broken.

Check the return value against -1 instead.  The test should only pass when
PTRACE_PEEKDATA fails, which means secret memory protection works.

Link: https://lore.kernel.org/20260910064415.71623-1-hongfu.li@linux.dev
Fixes: 76fe17ef588a ("secretmem: test: add basic selftest for memfd_secret(2)")
Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Bottomley <james.bottomley@HansenPartnership.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>

0 files changed, 0 insertions, 0 deletions