6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Florent Revest revest@chromium.org
[ Upstream commit a27e2e2d465e4ed73371974040689ac3e78fe3ee ]
I checked with the original author, the mmap_FIXED test case wasn't properly tested and fails. Currently, it maps two consecutive (non overlapping) pages and expects the second mapping to be denied by MDWE but these two pages have nothing to do with each other so MDWE is actually out of the picture here.
What the test actually intended to do was to remap a virtual address using MAP_FIXED. However, this operation unmaps the existing mapping and creates a new one so the va is backed by a new page and MDWE is again out of the picture, all remappings should succeed.
This patch keeps the test case to make it clear that this situation is expected to work: MDWE shouldn't block a MAP_FIXED replacement.
Link: https://lkml.kernel.org/r/20230828150858.393570-3-revest@chromium.org Fixes: 4cf1fe34fd18 ("kselftest: vm: add tests for memory-deny-write-execute") Signed-off-by: Florent Revest revest@chromium.org Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Kees Cook keescook@chromium.org Reviewed-by: Catalin Marinas catalin.marinas@arm.com Reviewed-by: Ryan Roberts ryan.roberts@arm.com Tested-by: Ryan Roberts ryan.roberts@arm.com Tested-by: Ayush Jain ayush.jain3@amd.com Cc: Alexey Izbyshev izbyshev@ispras.ru Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Greg Thelen gthelen@google.com Cc: Joey Gouly joey.gouly@arm.com Cc: KP Singh kpsingh@kernel.org Cc: Mark Brown broonie@kernel.org Cc: Michal Hocko mhocko@suse.com Cc: Peter Xu peterx@redhat.com Cc: Szabolcs Nagy Szabolcs.Nagy@arm.com Cc: Topi Miettinen toiwoton@gmail.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/mm/mdwe_test.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c index bc91bef5d254e..0c5e469ae38fa 100644 --- a/tools/testing/selftests/mm/mdwe_test.c +++ b/tools/testing/selftests/mm/mdwe_test.c @@ -168,13 +168,10 @@ TEST_F(mdwe, mmap_FIXED) self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0); ASSERT_NE(self->p, MAP_FAILED);
- p = mmap(self->p + self->size, self->size, PROT_READ | PROT_EXEC, + /* MAP_FIXED unmaps the existing page before mapping which is allowed */ + p = mmap(self->p, self->size, PROT_READ | PROT_EXEC, self->flags | MAP_FIXED, 0, 0); - if (variant->enabled) { - EXPECT_EQ(p, MAP_FAILED); - } else { - EXPECT_EQ(p, self->p); - } + EXPECT_EQ(p, self->p); }
TEST_F(mdwe, arm64_BTI)