linux-kernel - [PATCH v2 3/3] staging: fbtft: Add check on strlcpy() return value

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Message-Id: <1487129245-24970-4-git-send-email-me@tobin.cc>
Date:   Wed, 15 Feb 2017 14:27:25 +1100
From:   "Tobin C. Harding" <me@...in.cc>
To:     Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        noralf@...nnes.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        "Tobin C. Harding" <me@...in.cc>
Subject: [PATCH v2 3/3] staging: fbtft: Add check on strlcpy() return value

Return value of strlcpy() is not checked. Name string is silently
truncated if longer that SPI_NAME_SIZE, whilst not detrimental to
the program logic it would be nice to notify the user. Module is
currently quite verbose, adding extra pr_warn() calls will not overly
impact this verbosity.

Check return value from call to strlcpy(). If source string is
truncated call pr_warn() to notify user.

Signed-off-by: Tobin C. Harding <me@...in.cc>
---
 drivers/staging/fbtft/fbtft_device.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/fbtft/fbtft_device.c b/drivers/staging/fbtft/fbtft_device.c
index 5fbdd37..78baf46 100644
--- a/drivers/staging/fbtft/fbtft_device.c
+++ b/drivers/staging/fbtft/fbtft_device.c
@@ -1483,7 +1483,13 @@ static int __init fbtft_device_init(void)
 			displays[i].pdev->name = name;
 			displays[i].spi = NULL;
 		} else {
-			strlcpy(displays[i].spi->modalias, name, SPI_NAME_SIZE);
+			size_t len;
+
+			len = strlcpy(displays[i].spi->modalias, name,
+				SPI_NAME_SIZE);
+			if (len >= SPI_NAME_SIZE)
+				pr_warn("modalias (name) truncated to: %s\n",
+					displays[i].spi->modalias);
 			displays[i].pdev = NULL;
 		}
 	}
-- 
2.7.4