eeprom: at24: check at24_read/write arguments

commit d9bcd462 upstream.

So far we completely rely on the caller to provide valid arguments.
To be on the safe side perform an own sanity check.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/eeprom/at24.c

@@ -507,6 +507,9 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 	if (unlikely(!count))
 		return count;
 
+	if (off + count > at24->chip.byte_len)
+		return -EINVAL;
+
 	/*
 	 * Read data from chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.
@@ -539,6 +542,9 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 	if (unlikely(!count))
 		return -EINVAL;
 
+	if (off + count > at24->chip.byte_len)
+		return -EINVAL;
+
 	/*
 	 * Write data to chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.