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From:   Max Filippov <jcmvbkbc@gmail.com>
To:     Marco Elver <elver@google.com>
Cc:     Dmitry Vyukov <dvyukov@google.com>, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-xtensa@linux-xtensa.org,
        Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH v2] kcsan: test: don't put the expect array on the stack
Date:   Fri, 30 Dec 2022 16:45:14 -0800
Message-Id: <20221231004514.317809-1-jcmvbkbc@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Size of the 'expect' array in the __report_matches is 1536 bytes, which
is exactly the default frame size warning limit of the xtensa
architecture.
As a result allmodconfig xtensa kernel builds with the gcc that does not
support the compiler plugins (which otherwise would push the said
warning limit to 2K) fail with the following message:

  kernel/kcsan/kcsan_test.c:257:1: error: the frame size of 1680 bytes
    is larger than 1536 bytes

Fix it by dynamically alocating the 'expect' array.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
Changes v1->v2:
- add WARN_ON in case of kmalloc failure

 kernel/kcsan/kcsan_test.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c
index dcec1b743c69..a60c561724be 100644
--- a/kernel/kcsan/kcsan_test.c
+++ b/kernel/kcsan/kcsan_test.c
@@ -159,7 +159,7 @@ static bool __report_matches(const struct expect_report *r)
 	const bool is_assert = (r->access[0].type | r->access[1].type) & KCSAN_ACCESS_ASSERT;
 	bool ret = false;
 	unsigned long flags;
-	typeof(observed.lines) expect;
+	typeof(*observed.lines) *expect;
 	const char *end;
 	char *cur;
 	int i;
@@ -168,6 +168,10 @@ static bool __report_matches(const struct expect_report *r)
 	if (!report_available())
 		return false;
 
+	expect = kmalloc(sizeof(observed.lines), GFP_KERNEL);
+	if (WARN_ON(!expect))
+		return false;
+
 	/* Generate expected report contents. */
 
 	/* Title */
@@ -253,6 +257,7 @@ static bool __report_matches(const struct expect_report *r)
 		strstr(observed.lines[2], expect[1])));
 out:
 	spin_unlock_irqrestore(&observed.lock, flags);
+	kfree(expect);
 	return ret;
 }
 
-- 
2.30.2