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From: Arnd Bergmann <arnd@kernel.org>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	=?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>,
	linux-iio@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	llvm@lists.linux.dev
Subject: [PATCH] iio: avoid fortify-string overflow error
Date: Sat, 24 Feb 2024 13:11:34 +0100
Message-Id: <20240224121140.1883201-1-arnd@kernel.org>
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From: Arnd Bergmann <arnd@arndb.de>

The memcpy() call in dlhl60d.c triggers a check with clang-19:

In file included from drivers/iio/pressure/dlhl60d.c:11:
In file included from include/linux/module.h:17:
include/linux/fortify-string.h:553:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
  553 |                         __write_overflow_field(p_size_field, size);
      |                         ^

It writes into a two member array from a loop over a linked list
that likely has some indication of having more than two entries.

Add a conditional check there to avoid the overflow.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/iio/pressure/dlhl60d.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/pressure/dlhl60d.c b/drivers/iio/pressure/dlhl60d.c
index 28c8269ba65d..a43ecda849db 100644
--- a/drivers/iio/pressure/dlhl60d.c
+++ b/drivers/iio/pressure/dlhl60d.c
@@ -262,6 +262,8 @@ static irqreturn_t dlh_trigger_handler(int irq, void *private)
 			&st->rx_buf[1] + chn * DLH_NUM_DATA_BYTES,
 			DLH_NUM_DATA_BYTES);
 		i++;
+		if (i >= ARRAY_SIZE(tmp_buf))
+			break;
 	}
 
 	iio_push_to_buffers(indio_dev, tmp_buf);
-- 
2.39.2