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23 October 2021, 00:29:24 UTC
Revision d70674eeaa5efdefb99928691161578ae0a80316 authored by Arnd Bergmann on 25 October 2016, 15:55:04 UTC, committed by Greg Kroah-Hartman on 13 November 2016, 09:08:32 UTC 
iio: maxim_thermocouple: detect invalid storage size in read()
 
As found by gcc -Wmaybe-uninitialized, having a storage_bytes value other
than 2 or 4 will result in undefined behavior:

drivers/iio/temperature/maxim_thermocouple.c: In function 'maxim_thermocouple_read':
drivers/iio/temperature/maxim_thermocouple.c:141:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This probably cannot happen, but returning -EINVAL here is appropriate
and makes gcc happy and the code more robust.

Fixes: 231147ee77f3 ("iio: maxim_thermocouple: Align 16 bit big endian value of raw reads")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
(cherry picked from commit 32cb7d27e65df9daa7cee8f1fdf7b259f214bee2)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 parent 68fae2f
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Tip revision: d70674eeaa5efdefb99928691161578ae0a80316 authored by Arnd Bergmann on 25 October 2016, 15:55:04 UTC
iio: maxim_thermocouple: detect invalid storage size in read()
Tip revision: d70674e
int_sqrt.c 
/*
 * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com>
 *
 *  Based on the shift-and-subtract algorithm for computing integer
 *  square root from Guy L. Steele.
 */

#include <linux/kernel.h>
#include <linux/export.h>

/**
 * int_sqrt - rough approximation to sqrt
 * @x: integer of which to calculate the sqrt
 *
 * A very rough approximation to the sqrt() function.
 */
unsigned long int_sqrt(unsigned long x)
{
	unsigned long b, m, y = 0;

	if (x <= 1)
		return x;

	m = 1UL << (BITS_PER_LONG - 2);
	while (m != 0) {
		b = y + m;
		y >>= 1;

		if (x >= b) {
			x -= b;
			y += m;
		}
		m >>= 2;
	}

	return y;
}
EXPORT_SYMBOL(int_sqrt);
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