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From:   =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>
To:     =?UTF-8?q?Horia=20Geant=C4=83?= <horia.geanta@nxp.com>,
        Pankaj Gupta <pankaj.gupta@nxp.com>,
        Gaurav Jain <gaurav.jain@nxp.com>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        linux-crypto@vger.kernel.org, kernel@pengutronix.de
Subject: [PATCH] crypto: caam - Prevent fortify error
Date:   Thu, 22 Dec 2022 17:25:13 +0100
Message-Id: <20221222162513.4021928-1-u.kleine-koenig@pengutronix.de>
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Precedence: bulk

When compiling arm64 allmodconfig  with gcc 10.2.1 I get

	drivers/crypto/caam/desc_constr.h: In function ‘append_data.constprop’:
	include/linux/fortify-string.h:57:29: error: argument 2 null where non-null expected [-Werror=nonnull]

Fix this by skipping the memcpy if data is NULL and add a BUG_ON instead
that triggers on a problematic call that is now prevented to trigger.
After data == NULL && len != 0 is known to be false, logically

	if (len)
		memcpy(...)

could be enough to know that memcpy is not called with dest=NULL, but
gcc doesn't seem smart enough for that conclusion. gcc 12 doesn't have a
problem with the original code.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/crypto/caam/desc_constr.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/caam/desc_constr.h b/drivers/crypto/caam/desc_constr.h
index 62ce6421bb3f..163e0e740b11 100644
--- a/drivers/crypto/caam/desc_constr.h
+++ b/drivers/crypto/caam/desc_constr.h
@@ -163,7 +163,13 @@ static inline void append_data(u32 * const desc, const void *data, int len)
 {
 	u32 *offset = desc_end(desc);
 
-	if (len) /* avoid sparse warning: memcpy with byte count of 0 */
+	/*
+	 * avoid sparse warning: "memcpy with byte count of 0" and
+	 * and "error: argument 2 null where non-null expected
+	 * [-Werror=nonnull]" with fortify enabled.
+	 */
+	BUG_ON(data == NULL && len != 0);
+	if (len && data)
 		memcpy(offset, data, len);
 
 	(*desc) = cpu_to_caam32(caam32_to_cpu(*desc) +

base-commit: 9d2f6060fe4c3b49d0cdc1dce1c99296f33379c8
-- 
2.30.2