From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CBD3742885F; Sat, 12 Sep 2026 11:41:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789213267; cv=none; b=ji5Yi9oKaYL6ODggcBn/xZi1MSBsi9USDT8tjnR34uru/sfzsAtK2TOwq/5W6Llxd6SmNd0OlPweiRq6viUoMBUwypngOo6bLD+1Wpe0Pyn6FSBylY5r1DBhPBE96mxD0xylA9AmeBm6HQrb2A/V71GfUk/3Y6uljeIWS1t1SvU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789213267; c=relaxed/simple; bh=Jcmm/FPKGJ0DLMQNyVYTW5yKFnoC51SUBlHZjnmvgMA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fODS+EV1EAaXCzn8Au7hrNSU0I+x7OERCBUF2eRHKQtPD8wSkYY7MiOwvlHc9Z6CaQFjeTlE2CPKp8lShK85suXcPtcRPNYxAcl5DeFLaBXaunKThp0Qa8T1KM1XLDHvHCOoUAKUVjQPVMOzYN3JxnT/gwOyOphk9xyQbJ1d378= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TPfw6qMw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="TPfw6qMw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 862621F000FF; Sat, 12 Sep 2026 11:41:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789213265; bh=DzNjz3diR6djxRiM+1JGSCLVGzlz9AUJz/WPL09VwOo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=TPfw6qMw00ThwCvJrEB/6I1Lu49nppk2ZEjlZ2ZoPlsNsg0ztoneqZX4P/88kKgDa GJpAqmlq8T40rlTPEhkSAqWbz73UpM+3jeo3Tlg96mrHU1ZoddgDpOGy9hvhRvYIth wsqdF4dgZUt5Arv3ZyjrA3Qo+8+ignOY7fBIyZFE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, SJ Park , Brendan Higgins , Andrew Morton Subject: [PATCH 6.12 0049/1376] mm/damon/core-kunit: check region count before testing in split_at() Date: Sat, 12 Sep 2026 08:41:15 +0200 Message-ID: <20260912065608.651349126@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.535295758@linuxfoundation.org> References: <20260912065607.535295758@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: SJ Park commit 9b18ef3c3aa1ce24176e340061caf15fa2742564 upstream. damon_test_split_at() test next region that is assumed to be created by damon_split_region_at() invocation. But the split might fail. In this case, the succeeding test may dereference invalid pointers returned by damon_next_region(). The invalid pointer may not cause a really bad user impact, because of the implementation detail. It would only read wrong contents in the belonging damon_target struct. Depending on the future change of the offset from the link header to the accessing field, this could also be really dangerous, though. Still, the realistic user impact would be limited. 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. Link: https://lore.kernel.org/20260718001442.87129-3-sj@kernel.org Link: https://lore.kernel.org/20260714142352.100478-1-sj@kernel.org [1] Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests") Signed-off-by: SJ Park Cc: Brendan Higgins Cc: # 5.15.x Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/damon/tests/core-kunit.h | 5 +++++ 1 file changed, 5 insertions(+) --- a/mm/damon/tests/core-kunit.h +++ b/mm/damon/tests/core-kunit.h @@ -166,6 +166,10 @@ static void damon_test_split_at(struct k r->last_nr_accesses = 15; damon_add_region(r, t); damon_split_region_at(t, r, 25); + KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 2); + if (damon_nr_regions(t) != 2) + goto out; + KUNIT_EXPECT_EQ(test, r->ar.start, 0ul); KUNIT_EXPECT_EQ(test, r->ar.end, 25ul); @@ -177,6 +181,7 @@ static void damon_test_split_at(struct k KUNIT_EXPECT_EQ(test, r->nr_accesses, r_new->nr_accesses); KUNIT_EXPECT_EQ(test, r->last_nr_accesses, r_new->last_nr_accesses); +out: damon_free_target(t); damon_destroy_ctx(c); }