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b=Dk5Y5mnL4n9nX/qD+riWA/ocT3wlzIvV64mCeq4BIDPZnxhLoxScdDhMwdgNFf7zF 2iA2J60FRi0QCcK9b/Ev3kZn6isdq6kJon5KOwDi1aXFlthjXVHBdMcaO4pe/GSl2S WdXeCd/lBbclbCT+ttbP9Vv7ictIL/0tNSMQcdiWd0zj0RD4ayuhATuniAyn4W0pWo CY5xNFiqvWohcGTK/G6HGuUkRaSea9ew6LC4ldMnjwmdvKLpN/6SUd3aOyC//s3a9l OS0a2uoubtWa0f+1KwryUzcHcrv0xMKGY9cDmLyCKWKB2tDcK5qriW2xupwwAM8y9A N+JY9ISM6Qb7w== From: SJ Park To: Andrew Morton Cc: SJ Park , stable@vger.kernel.org, Brendan Higgins , David Gow , SeongJae Park , damon@lists.linux.dev, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 3/7] mm/damon/vaddr-kunit: check region count in three_regions test Date: Fri, 17 Jul 2026 17:14:37 -0700 Message-ID: <20260718001442.87129-4-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260718001442.87129-1-sj@kernel.org> References: <20260718001442.87129-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B6ABC20004 X-Stat-Signature: nf73pger9gaeqfecetcjm8hadwf4f3b9 X-HE-Tag: 1784333686-827113 X-HE-Meta: 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 soUK3u3a 4pNu/jH3mzyeWLP9D48w5viC4oJZLF4nMuzilCYsesR76oGT4E5eqBQw3yVBLrwCM5yr8C+ekAGKPDy6a6d/CWLmpmS0zyOM7dHImI207EePRTzOxbmKcacJuxVM3eG9P9I8+y04ExnVYmAKGwbKlQwoQ2WR6oaRjepKHIOJ+rMIwFm9TJfOIVWaVTFm00u3+UNSWroSRdtc2B5V3bJ00NgkvYtSX8ibJKuP/PcYQNMmPr3tMQJELP/ZMAtBGDSkRwebvSS9Caog6uV3u7BWbKGy7rpplHeaqrL7hkjNawSYrqhZyqCrcFi4iAjcKnBH/wZcg Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: damon_do_test_apply_three_regions() iterates regions after damon_set_regions() call assuming the function would succeed at setting the number of regions the same to the expected one. It might have failed. In this case, __nth_region_of() in the iteration could return NULL and NULL dereference can happen in the test. The consequent user impact (NULL dereference) is quite bad. The realistic user impact would be limited, though. It would affect only test run setups. Fix it by testing if the number of regions was also changed as expected and exit early for the failure. The issue was discovered [1] by Sashiko. [1] https://lore.kernel.org/20260713144757.39740-1-sj@kernel.org Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests") Cc: # 5.15.x Signed-off-by: SJ Park --- mm/damon/tests/vaddr-kunit.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/damon/tests/vaddr-kunit.h b/mm/damon/tests/vaddr-kunit.h index 61f844336ffb5..6a95441d193ae 100644 --- a/mm/damon/tests/vaddr-kunit.h +++ b/mm/damon/tests/vaddr-kunit.h @@ -158,12 +158,17 @@ static void damon_do_test_apply_three_regions(struct kunit *test, kunit_skip(test, "second damon_set_regions() fail"); } + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), nr_expected / 2); + if (damon_nr_regions(t) != nr_expected / 2) + goto out; + for (i = 0; i < nr_expected / 2; i++) { r = __nth_region_of(t, i); KUNIT_EXPECT_EQ(test, r->ar.start, expected[i * 2]); KUNIT_EXPECT_EQ(test, r->ar.end, expected[i * 2 + 1]); } +out: damon_destroy_target(t, NULL); } -- 2.47.3