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b=jAmFrdPY24XYQ5acDhq7jYcbFZYkwynaIqmqMPtnVezWvFejovFVxwCFlwpRvPx14 06wZVFqeO37V8QGxAOu3+2PE/V95PPU/bId3A4HL5wH0Xt5ZjbDYX9eciKZd2vLRlm DsY2T580QzVOcjGrA13jhqCWtzdY4rj8IMGgkq5rK/87t2XSI5nVElYCsNqFnJ8szQ nCN9staruM05HlIJyLIwjwhBZx3aV+g2NBE8L7HthHO4oTaNX3fbwJ2VrVU5lvTlyE TgpxUiV3n4va0xkg+KOIwu3KzUJ7Z5C2c3YrBK5o1d2SqyPB3ikoFuOzew0AxisEKl ytjn4DAXvz8yw== From: SJ Park To: Cc: SJ Park , stable@vger.kernel.org, Andrew Morton , 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: [RFC PATCH v1.1 3/7] mm/damon/vaddr-kunit: check region count in three_regions test Date: Fri, 17 Jul 2026 07:34:40 -0700 Message-ID: <20260717143445.91207-4-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260717143445.91207-1-sj@kernel.org> References: <20260717143445.91207-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 4F580180013 X-Stat-Signature: csxoqppfjc136nhea6f7jb536pdh8497 X-HE-Tag: 1784298895-242607 X-HE-Meta: U2FsdGVkX19qEoFgulrd4wcJKSnNsPF+5GcD/pMHVtvNHFVMPD0c1q9gdZ7Ilbs46tUM4QgGGuCdYkr7WBnjIxyy1dvrC1norRurn23KcdthxkaqbdBempDQjC7bHPYI4ZWU1EBzfm18jPuSwkq6x05kVBOTRuKWYNjwOxhT2cAZ5ApDjtlGzTnNVaByPoAqPwxkbbfBLwxcM1bYKP+d2XJCxRxsYfZFQlb/2dA6BajwEnC4TcAoD9UIekpUowwNY6IkIbUMdmcH0M0RWDB8vNa0ED10W1onrHOCuNegb2JkJJr4ysFynxi139SZ2R7pt7ZV+hZGrLD8xe8hgxGDaOJKBhO/1EqZGxi9WSlGcAoznCIw+EJzzGqRu1yQPY8LvIkZ7MD8mfQJXZx0ptsWOBzI4bOLfni4QflZCRNcJcTeL8moZ5Fu87xqugm5+DsbyCdLZiCuUlKC3CJOxDbiVQmaJ/pOGrdBZxO7fDOiQeVTEwovWetQ0svCWlGfKNmXQiVDXzbc0a8VGdare/QX0oByUSl1WvzFo+/Zl9XjDbWJIjxllBx40LFBJ8kzYxz9+0bJ2mxYloKmAFiebvvrmNeciBjUa1vmKxJLgLnSqu1iUD5UXNh0GUHR/rQZ0TDwSdZSTnW/zY88UL/W+zZA4U9ejX4oka42wIROB9koNis/IEuitRfZZrEmz9RBBTbrf9Rnfk/HoX93tk5rK42Wt6f6qxnRIX7AqNHr7tIWilxWU7hC94faML0DmPcYt2a+a0wdluecizCBt+6SbaSSpkAjuRtgp/Crq58BN72mOXWbZ1zR7OZQbshor0fHzrje5Vd9BBzE+RXY2gmvi3ccrLFxyhSitccj+W4H0HuPy/LQHhA4SSnnSgQAVcWuvxm4g/JgIUgS0NtwHL8S5ZwEKq8dq+JGe3QyEXTMrklQK3i+K8bYaMgStIERGOkobdNUyjJnLVaTxU4+IzWKift 4lXRfWG6 0YLX+9Dm9fHQkapJQi/eS2Mf7zuLjVbZPcrDnHY9VdFB7ZB3WkTinrcGKGd0B4iujW3WSklo2hspXvlIpn0ZtUo3wWDdk/aLvKuBnkFX9pTCTrOpFp+LL36hBtHSaQW3uSyJ0wjeYOHg8r96jdxraR2RVmioI9wZ6tFXAYeY/JzkViv97HQSrVkn+bpPzX/cPJc0Vcy18GlO1wUH0dzUgqPTy8cEC0Cf5hCgjyY4nr3svhntR1wULLUBPJDhdZOvxec1vs9kw+OWl5ht2YKLdO23zPm0uefpBe3MXDjgRiFYuuLprEnVBK6uxi5I/muTmWiXK 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