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Commit c44ba9f6 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

lib/checksum.c: use 32-bit arithmetic consistently 



The use of 'unsigned long' variables in the 32-bit part of do_csum()
is confusing at best, and potentially broken for long input on 64-bit
machines.

This changes the code to use 'unsigned int' instead, which makes
the code behave in the same (correct) way on both 32 and 64 bit
machines.

Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent b6727b12

lib/checksum.c

+4 −4
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ 


#include <asm/byteorder.h>



static inline unsigned short from32to16(unsigned long x)

static inline unsigned short from32to16(unsigned int x)

{

	/* add up 16-bit and 16-bit for 16+c bit */

	x = (x & 0xffff) + (x >> 16);
@@ -49,7 +49,7 @@ static inline unsigned short from32to16(unsigned long x) 
static unsigned int do_csum(const unsigned char *buff, int len)

{

	int odd, count;

	unsigned long result = 0;

	unsigned int result = 0;



	if (len <= 0)

		goto out;
@@ -73,9 +73,9 @@ static unsigned int do_csum(const unsigned char *buff, int len) 
		}

		count >>= 1;		/* nr of 32-bit words.. */

		if (count) {

			unsigned long carry = 0;

			unsigned int carry = 0;

			do {

				unsigned long w = *(unsigned int *) buff;

				unsigned int w = *(unsigned int *) buff;

				count--;

				buff += 4;

				result += carry;