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: Linus Torvalds <[email protected]> Signed-off-by: Arnd Bergmann <[email protected]>
MkSavin · Nov 3, 2009 · c44ba9f · c44ba9f
1 parent b6727b1
commit c44ba9f
Showing 1 changed file with 4 additions and 4 deletions.
diff --git a/lib/checksum.c b/lib/checksum.c
@@ -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;