From 9c74367665226a1230a88985b6a4c37d66c69940 Mon Sep 17 00:00:00 2001 From: Florent Revest Date: Mon, 28 Aug 2023 17:08:54 +0200 Subject: [PATCH] kselftest: vm: fix mdwe's mmap_FIXED test case [ 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 Reviewed-by: David Hildenbrand Reviewed-by: Kees Cook Reviewed-by: Catalin Marinas Reviewed-by: Ryan Roberts Tested-by: Ryan Roberts Tested-by: Ayush Jain Cc: Alexey Izbyshev Cc: Anshuman Khandual Cc: Greg Thelen Cc: Joey Gouly Cc: KP Singh Cc: Mark Brown Cc: Michal Hocko Cc: Peter Xu Cc: Szabolcs Nagy Cc: Topi Miettinen Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- 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 bc91bef..0c5e469 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) -- 2.7.4